Q9Z2R9 (E2AK1_MOUSE) Reviewed, UniProtKB/Swiss-Prot

Names and origin

Protein names

Recommended name:
Eukaryotic translation initiation factor 2-alpha kinase 1
EC=2.7.11.1

Alternative name(s):
Heme-controlled repressor
Short name=HCR
Heme-regulated eukaryotic initiation factor eIF-2-alpha kinase
Heme-regulated inhibitor
Hemin-sensitive initiation factor 2-alpha kinase

Gene names

Name:	Eif2ak1
Synonyms:	Hri

Organism

Mus musculus (Mouse) [Reference proteome]

Taxonomic identifier

10090 [NCBI]

Taxonomic lineage

cellular organisms › Eukaryota › Opisthokonta › Metazoa › Eumetazoa › Bilateria › Deuterostomia › Chordata › Craniata › Vertebrata › Gnathostomata › Teleostomi › Euteleostomi › Sarcopterygii › Tetrapoda › Amniota › Mammalia › Theria › Eutheria › Euarchontoglires › Glires › Rodentia › Sciurognathi › Muroidea › Muridae › Murinae › Mus › Mus

Protein attributes

Sequence length	619 AA.
Sequence status	Complete.
Protein existence	Evidence at protein level

General annotation (Comments)

Function	Inhibits protein synthesis at the translation initiation level, in response to various stress conditions, including oxidative stress, heme deficiency, osmotic shock and heat shock. Exerts its function through the phosphorylation of EIF2S1 at 'Ser-48' and 'Ser-51', thus preventing its recycling. Binds hemin forming a 1:1 complex through a cysteine thiolate and histidine nitrogenous coordination. This binding occurs with moderate affinity, allowing it to sense the heme concentration within the cell. Thanks to this unique heme-sensing capacity, plays a crucial role to shut off protein synthesis during acute heme-deficient conditions. In red blood cells (RBCs), controls hemoglobin synthesis ensuring a coordinated regulation of the synthesis of its heme and globin moieties. Thus plays an essential protective role for RBC survival in anemias of iron deficiency. Similarly, in hepatocytes, involved in heme-mediated translational control of CYP2B and CYP3A and possibly other hepatic P450 cytochromes. May also contain ER stress during acute heme-deficient conditions. Ref.2 Ref.10 Ref.12
Catalytic activity	ATP + a protein = ADP + a phosphoprotein.
Enzyme regulation	Induced by acute heme depletion, that not only increases EIF2AK1 protein levels, but also stimulates kinase activity by autophosphorylation. Inhibited by the heme-degradation products biliverdin and bilirubin. Induced by oxidative stress generated by arsenite treatment. Binding of nitric oxide (NO) to the heme iron in the N-terminal heme-binding domain activates the kinase activity, while binding of carbon monoxide (CO) suppresses kinase activity. Ref.8 Ref.9 Ref.12
Subunit structure	Synthesized in an inactive form that binds to the N-terminal domain of CDC37. Has to be associated with a multiprotein complex containing Hsp90, CDC37 and PPP5C for maturation and activation by autophosphorylation. The phosphatase PPP5C modulates this activation By similarity. Forms oligomers. Has been reported as a homodimer, as well as a hexamer in the absence of hemin. Converted to an inactive disulfide linked homodimer in the presence of hemin. Ref.10
Subcellular location	Cytoplasm Ref.11.
Tissue specificity	Expressed predominantly in erythroid cells, mature reticulocytes, as well as fetal liver nucleated erythroid cells. At much lower levels, expressed in hepatocytes and bone marrow-derived macrophages (at protein level). Ref.7 Ref.11 Ref.12
Developmental stage	Highly expressed in fetal liver erythroid precursor cells at 14.5 dpc (at protein level). Ref.11
Induction	By phenobarbital. Ref.7 Ref.8 Ref.9 Ref.10 Ref.12
Post-translational modification	Activated by autophosphorylation; phosphorylated predominantly on serine and threonine residues, but also on tyrosine residues. Autophosphorylation at Thr-485 is required for kinase activation. The active autophosphorylated form apparently is largely refractory to cellular heme fluctuations. Ref.1 Ref.6 Ref.8
Involvement in disease	Defects in Eif2ak1 are a cause of hyperchromic anemia in animals suffering from iron deficiency. The number of red blood cells is decreased due to increased apoptosis of erythroid precursor cells, probably because globins misfold and aggregate in the absence of heme.
Disruption phenotype	Mice are viable and fertile without gross morphological abnormalities. Dramatically altered response to diet-induced iron deficiency shifting from an adaptive decrease in RBC volume and intracellular hemoglobin content to an increased production of abnormally dense red blood cells (RBCs) with decreasing red cell counts. The decrease in RBC number is the result of increased apoptosis of erythroid precursors. Diminished levels of phosphorylated EIF2S1 in bone marrow-derived macrophages (BMDMs). Impaired maturation of BMDMs and blunted inflammatory response to LPS with a reduced cytokine production. Impaired phagocytosis of senescent RBCs by macrophages, resulting in a lower phagocytosis index and lower percentage of macrophages with ingested RBC. In hepatocytes, cytochromes P450 CYP2B6 and CYP3A induction by phenobarbital is not impaired in response to acute heme depletion and CYP2B6 and CYP3A proteins continue to accumulate to supranormal levels, irrespective of the hepatic heme pool status. These cells also exhibit a weak, albeit significant, elevation of the basal ER-stress as reflected by elevated levels of autophosphorylated EIF2AK3/PERK and EIF2AK4/GCN2, the ER-stress related chaperones HSPA5 and HSP90B1, and total hepatic protein ubiquitination. Ref.2 Ref.11 Ref.12
Sequence similarities	Belongs to the protein kinase superfamily. Ser/Thr protein kinase family. GCN2 subfamily. Contains 2 HRM (heme regulatory motif) repeats. Contains 1 protein kinase domain.
Sequence caution	The sequence BAD32438.1 differs from that shown. Reason: Erroneous initiation. Translation N-terminally shortened.

Ontologies

Keywords
Cellular component	Cytoplasm
Domain	Repeat
Ligand	ATP-binding Nucleotide-binding
Molecular function	Kinase Protein synthesis inhibitor Serine/threonine-protein kinase Transferase
PTM	Disulfide bond Phosphoprotein
Technical term	Complete proteome Reference proteome
Gene Ontology (GO)
Biological_process	negative regulation of cell proliferation Inferred from direct assay PubMed 11050009. Source: UniProtKB negative regulation of hemoglobin biosynthetic process Inferred from direct assay PubMed 11050009. Source: UniProtKB negative regulation of translation Inferred from electronic annotation. Source: UniProtKB-KW protein autophosphorylation Inferred from expression pattern Ref.6. Source: UniProtKB protoporphyrinogen IX metabolic process Inferred from genetic interaction PubMed 15931390. Source: MGI regulation of eIF2 alpha phosphorylation by heme Inferred from genetic interaction PubMed 15931390. Source: MGI regulation of translation Inferred from mutant phenotype Ref.2. Source: MGI response to external stimulus Inferred from sequence or structural similarity. Source: UniProtKB response to stress Inferred from sequence or structural similarity. Source: UniProtKB
Cellular_component	cytoplasm Inferred from direct assay PubMed 11050009. Source: UniProtKB
Molecular_function	ATP binding Inferred from electronic annotation. Source: UniProtKB-KW eukaryotic translation initiation factor 2alpha kinase activity Inferred from sequence or structural similarity. Source: UniProtKB heme binding Inferred from direct assay PubMed 10671563. Source: UniProtKB
Complete GO annotation...

Sequence annotation (Features)

	Feature key	Position(s)	Length	Description	Graphical view	Feature identifier
Molecule processing
	Chain	1 – 619	619	Eukaryotic translation initiation factor 2-alpha kinase 1		PRO_0000085942
Regions
	Domain	167 – 580	414	Protein kinase
	Repeat	408 – 413	6	HRM 1
	Repeat	549 – 554	6	HRM 2
	Nucleotide binding	173 – 181	9	ATP By similarity
Sites
	Active site	440	1	Proton acceptor By similarity
	Binding site	196	1	ATP By similarity
	Site	80	1	Heme-binding By similarity
Amino acid modifications
	Modified residue	483	1	Phosphothreonine; by autocatalysis Ref.8
	Modified residue	485	1	Phosphothreonine; by autocatalysis Ref.8
Experimental info
	Mutagenesis	196	1	K → R: Abolishes kinase activity. Ref.1 Ref.8
	Mutagenesis	483	1	T → A: No effect on kinase activity. Ref.8
	Mutagenesis	483	1	T → D: No effect on kinase activity. Ref.8
	Mutagenesis	485	1	T → A: Abolishes kinase activity. Ref.8
	Mutagenesis	485	1	T → D: Constitutively active kinase; loss of regulation by heme and arsenite. Ref.8
	Mutagenesis	490	1	T → A: Almost complete loss of kinase activity; even upon arsenite treatment. Ref.8
	Mutagenesis	490	1	T → D: Almost complete loss of kinase activity; even upon arsenite treatment. Ref.8
	Sequence conflict	20	1	A → S in BAB32242. Ref.5
	Sequence conflict	71	1	S → C in BAB32242. Ref.5
	Sequence conflict	138 – 150	13	DPCQD…MQKIR → VSPTGCTLYDKYI in BAB32242. Ref.5
	Sequence conflict	196 – 197	2	KK → IE in BAB29545. Ref.5
	Sequence conflict	371	1	E → D in AAC79201. Ref.1
	Sequence conflict	371	1	E → D in AAK55766. Ref.2
	Sequence conflict	565	1	V → A in AAH28923. Ref.4

Sequences

	Sequence		Length	Mass (Da)
	Q9Z2R9 [UniParc]. Last modified April 5, 2011. Version 2. Checksum: 39DC5FF950C92F2A	FASTA	619	69,702
	10 20 30 40 50 60 MLGGSSVDGE RDTDDDAAGA VAAPPAIDFP AEVSDPKYDE SDVPAELQVL KEPLQQPTFP 70 80 90 100 110 120 FLVANQLLLV SLLEHLSHVH EPNPLHSKQV FKLLCQTFIK MGLLSSFTCS DEFSSLRLHH 130 140 150 160 170 180 NRAITHLMRS AKERVRQDPC QDNSYMQKIR SREIAFEAQT SRYLNEFEEL AILGKGGYGR 190 200 210 220 230 240 VYKVRNKLDG QHYAIKKILI KSATKTDCMK VLREVKVLAG LQHPNIVGYH TAWIEHVHVV 250 260 270 280 290 300 QPQDRVPIQL PSLEVLSEQE GDRDQGGVKD NESSSSIVFA ELTPEKEKPF GESEVKNENN 310 320 330 340 350 360 NLVSYTANLV VRNSSESESS IELQEDGLTD LSVRPVVRHQ LPLGHSSELE GNFTSTDESS 370 380 390 400 410 420 EGNLNLLGQT EVRYHLMLHI QMQLCELSLW DWITERNKRS REYVDEAACP YVMASVATKI 430 440 450 460 470 480 FQELVEGVFY IHNMGIVHRD LKPRNIFLHG PDQQVKIGDF GLACADIIQN ADWTNRNGKG 490 500 510 520 530 540 TRTHTSRVGT CLYASPEQLE GSQYDAKSDM YSLGVILLEL FQPFGTEMER ATVLTGVRTG 550 560 570 580 590 600 RIPESLSKRC PVQAKYIQLL TGRNVSQRPS ALQLLQSELF QTTGNVNLTL QMKIIEQEKE 610 IEELKKQLSL LSQDRGLKR

References

	« Hide 'large scale' referencesShow 'large scale' references »
[1]	"Characterization of the hemin-sensitive eukaryotic initiation factor 2alpha kinase from mouse nonerythroid cells." Berlanga J.J., Herrero S., de Haro C. J. Biol. Chem. 273:32340-32346(1998) [PubMed] [Europe PMC] [Abstract] Cited for: NUCLEOTIDE SEQUENCE [MRNA], MUTAGENESIS OF LYS-196, AUTOPHOSPHORYLATION. Strain: C57BL/6 X CBA. Tissue: Liver.
[2]	"Heme-regulated eIF2alpha kinase (HRI) is required for translational regulation and survival of erythroid precursors in iron deficiency." Han A.-P., Yu C., Lu L., Fujiwara Y., Browne C., Chin G., Fleming M., Leboulch P., Orkin S.H., Chen J.-J. EMBO J. 20:6909-6918(2001) [PubMed] [Europe PMC] [Abstract] Cited for: NUCLEOTIDE SEQUENCE [MRNA], FUNCTION, DISRUPTION PHENOTYPE. Tissue: Erythroleukemia.
[3]	"Prediction of the coding sequences of mouse homologues of KIAA gene: IV. The complete nucleotide sequences of 500 mouse KIAA-homologous cDNAs identified by screening of terminal sequences of cDNA clones randomly sampled from size-fractionated libraries." Okazaki N., Kikuno R., Ohara R., Inamoto S., Koseki H., Hiraoka S., Saga Y., Seino S., Nishimura M., Kaisho T., Hoshino K., Kitamura H., Nagase T., Ohara O., Koga H. DNA Res. 11:205-218(2004) [PubMed] [Europe PMC] [Abstract] Cited for: NUCLEOTIDE SEQUENCE [LARGE SCALE MRNA]. Tissue: Pancreatic islet.
[4]	"The status, quality, and expansion of the NIH full-length cDNA project: the Mammalian Gene Collection (MGC)." The MGC Project Team Genome Res. 14:2121-2127(2004) [PubMed] [Europe PMC] [Abstract] Cited for: NUCLEOTIDE SEQUENCE [LARGE SCALE MRNA]. Strain: C57BL/6J and FVB/N. Tissue: Eye and Salivary gland.
[5]	"The transcriptional landscape of the mammalian genome." Carninci P., Kasukawa T., Katayama S., Gough J., Frith M.C., Maeda N., Oyama R., Ravasi T., Lenhard B., Wells C., Kodzius R., Shimokawa K., Bajic V.B., Brenner S.E., Batalov S., Forrest A.R., Zavolan M., Davis M.J. , Wilming L.G., Aidinis V., Allen J.E., Ambesi-Impiombato A., Apweiler R., Aturaliya R.N., Bailey T.L., Bansal M., Baxter L., Beisel K.W., Bersano T., Bono H., Chalk A.M., Chiu K.P., Choudhary V., Christoffels A., Clutterbuck D.R., Crowe M.L., Dalla E., Dalrymple B.P., de Bono B., Della Gatta G., di Bernardo D., Down T., Engstrom P., Fagiolini M., Faulkner G., Fletcher C.F., Fukushima T., Furuno M., Futaki S., Gariboldi M., Georgii-Hemming P., Gingeras T.R., Gojobori T., Green R.E., Gustincich S., Harbers M., Hayashi Y., Hensch T.K., Hirokawa N., Hill D., Huminiecki L., Iacono M., Ikeo K., Iwama A., Ishikawa T., Jakt M., Kanapin A., Katoh M., Kawasawa Y., Kelso J., Kitamura H., Kitano H., Kollias G., Krishnan S.P., Kruger A., Kummerfeld S.K., Kurochkin I.V., Lareau L.F., Lazarevic D., Lipovich L., Liu J., Liuni S., McWilliam S., Madan Babu M., Madera M., Marchionni L., Matsuda H., Matsuzawa S., Miki H., Mignone F., Miyake S., Morris K., Mottagui-Tabar S., Mulder N., Nakano N., Nakauchi H., Ng P., Nilsson R., Nishiguchi S., Nishikawa S., Nori F., Ohara O., Okazaki Y., Orlando V., Pang K.C., Pavan W.J., Pavesi G., Pesole G., Petrovsky N., Piazza S., Reed J., Reid J.F., Ring B.Z., Ringwald M., Rost B., Ruan Y., Salzberg S.L., Sandelin A., Schneider C., Schoenbach C., Sekiguchi K., Semple C.A., Seno S., Sessa L., Sheng Y., Shibata Y., Shimada H., Shimada K., Silva D., Sinclair B., Sperling S., Stupka E., Sugiura K., Sultana R., Takenaka Y., Taki K., Tammoja K., Tan S.L., Tang S., Taylor M.S., Tegner J., Teichmann S.A., Ueda H.R., van Nimwegen E., Verardo R., Wei C.L., Yagi K., Yamanishi H., Zabarovsky E., Zhu S., Zimmer A., Hide W., Bult C., Grimmond S.M., Teasdale R.D., Liu E.T., Brusic V., Quackenbush J., Wahlestedt C., Mattick J.S., Hume D.A., Kai C., Sasaki D., Tomaru Y., Fukuda S., Kanamori-Katayama M., Suzuki M., Aoki J., Arakawa T., Iida J., Imamura K., Itoh M., Kato T., Kawaji H., Kawagashira N., Kawashima T., Kojima M., Kondo S., Konno H., Nakano K., Ninomiya N., Nishio T., Okada M., Plessy C., Shibata K., Shiraki T., Suzuki S., Tagami M., Waki K., Watahiki A., Okamura-Oho Y., Suzuki H., Kawai J., Hayashizaki Y. Science 309:1559-1563(2005) [PubMed] [Europe PMC] [Abstract] Cited for: NUCLEOTIDE SEQUENCE [LARGE SCALE MRNA] OF 1-211 AND 445-619. Strain: C57BL/6J. Tissue: Head, Olfactory bulb and Retina.
[6]	"Multiple autophosphorylation is essential for the formation of the active and stable homodimer of heme-regulated eIF2alpha kinase." Bauer B.N., Rafie-Kolpin M., Lu L., Han A., Chen J.-J. Biochemistry 40:11543-11551(2001) [PubMed] [Europe PMC] [Abstract] Cited for: AUTOPHOSPHORYLATION ON SERINE; THREONINE AND TYROSINE RESIDUES, HEME-BINDING.
[7]	"Translation initiation control by heme-regulated eukaryotic initiation factor 2alpha kinase in erythroid cells under cytoplasmic stresses." Lu L., Han A.P., Chen J.J. Mol. Cell. Biol. 21:7971-7980(2001) [PubMed] [Europe PMC] [Abstract] Cited for: REGULATION BY HEME DEFICIENCY; HEAT SHOCK; OSMOTIC STRESS AND OXIDATIVE STRESS, TISSUE SPECIFICITY.
[8]	"Autophosphorylation of threonine 485 in the activation loop is essential for attaining eIF2alpha kinase activity of HRI." Rafie-Kolpin M., Han A.P., Chen J.J. Biochemistry 42:6536-6544(2003) [PubMed] [Europe PMC] [Abstract] Cited for: AUTOPHOSPHORYLATION AT THR-483; THR-485 AND THR-490, ENZYME REGULATION, MUTAGENESIS OF LYS-196; THR-483; THR-485 AND THR-490.
[9]	"Activation of heme-regulated eukaryotic initiation factor 2alpha kinase by nitric oxide is induced by the formation of a five-coordinate NO-heme complex: optical absorption, electron spin resonance, and resonance raman spectral studies." Igarashi J., Sato A., Kitagawa T., Yoshimura T., Yamauchi S., Sagami I., Shimizu T. J. Biol. Chem. 279:15752-15762(2004) [PubMed] [Europe PMC] [Abstract] Cited for: HEME-BINDING, ENZYME REGULATION.
[10]	"Characterization of heme-regulated eIF2alpha kinase: roles of the N-terminal domain in the oligomeric state, heme binding, catalysis, and inhibition." Miksanova M., Igarashi J., Minami M., Sagami I., Yamauchi S., Kurokawa H., Shimizu T. Biochemistry 45:9894-9905(2006) [PubMed] [Europe PMC] [Abstract] Cited for: FUNCTION, OLIGOMERIZATION, HEME-BINDING, INDUCTION.
[11]	"The function of heme-regulated eIF2alpha kinase in murine iron homeostasis and macrophage maturation." Liu S., Suragani R.N., Wang F., Han A., Zhao W., Andrews N.C., Chen J.J. J. Clin. Invest. 117:3296-3305(2007) [PubMed] [Europe PMC] [Abstract] Cited for: SUBCELLULAR LOCATION, TISSUE SPECIFICITY, DEVELOPMENTAL STAGE, DISRUPTION PHENOTYPE.
[12]	"Hepatic heme-regulated inhibitor (HRI) eukaryotic initiation factor 2alpha kinase: a protagonist of heme-mediated translational control of CYP2B enzymes and a modulator of basal endoplasmic reticulum stress tone." Acharya P., Chen J.J., Correia M.A. Mol. Pharmacol. 77:575-592(2010) [PubMed] [Europe PMC] [Abstract] Cited for: FUNCTION, TISSUE SPECIFICITY, ENZYME REGULATION, DISRUPTION PHENOTYPE.
+	Additional computationally mapped references.

Cross-references

Sequence databases
EMBL GenBank DDBJ	AF028808 mRNA. Translation: AAC79201.1. AY033898 mRNA. Translation: AAK55766.1. AK173160 mRNA. Translation: BAD32438.1. Different initiation. BC028923 mRNA. Translation: AAH28923.1. BC111035 mRNA. Translation: AAI11036.1. AK014775 mRNA. Translation: BAB29545.1. AK020887 mRNA. Translation: BAB32242.1. AK032508 mRNA. Translation: BAC27901.1.
IPI	IPI00131320.
RefSeq	NP_038585.2. NM_013557.2.
UniGene	Mm.389709. Mm.431968.
3D structure databases
ProteinModelPortal	Q9Z2R9.
SMR	Q9Z2R9. Positions 162-235, 378-619.
ModBase	Search...
Protein-protein interaction databases
IntAct	Q9Z2R9. 1 interaction.
STRING	10090.ENSMUSP00000098056.
PTM databases
PhosphoSite	Q9Z2R9.
Proteomic databases
PRIDE	Q9Z2R9.
Protocols and materials databases
StructuralBiologyKnowledgebase	Search...
Genome annotation databases
Ensembl	ENSMUST00000100487; ENSMUSP00000098056; ENSMUSG00000029613.
GeneID	15467.
KEGG	mmu:15467.
Organism-specific databases
CTD	27102.
MGI	MGI:1353448. Eif2ak1.
Phylogenomic databases
eggNOG	COG0515.
GeneTree	ENSGT00530000062984.
HOVERGEN	HBG051429.
InParanoid	Q69ZK8.
KO	K16194.
OMA	GYHTAWM.
OrthoDB	EOG43FGWK.
Gene expression databases
ArrayExpress	Q9Z2R9.
Bgee	Q9Z2R9.
Genevestigator	Q9Z2R9.
GermOnline	ENSMUSG00000029613. Mus musculus.
Family and domain databases
InterPro	IPR015516. Haem-reg_EIF2A_Kinase. IPR011009. Kinase-like_dom. IPR000719. Prot_kinase_cat_dom. IPR017441. Protein_kinase_ATP_BS. IPR008271. Ser/Thr_kinase_AS. [Graphical view]
PANTHER	PTHR11042:SF16. PTHR11042:SF16. 1 hit.
Pfam	PF00069. Pkinase. 2 hits. [Graphical view]
SUPFAM	SSF56112. Kinase_like. 1 hit.
PROSITE	PS00107. PROTEIN_KINASE_ATP. 1 hit. PS50011. PROTEIN_KINASE_DOM. 1 hit. PS00108. PROTEIN_KINASE_ST. 1 hit. [Graphical view]
ProtoNet	Search...
Other
ChEMBL	CHEMBL1938213.
ChiTaRS	EIF2AK1. mouse.
NextBio	288300.
SOURCE	Search...

Entry information

Entry name

E2AK1_MOUSE

Accession

Primary (citable) accession number: Q9Z2R9
Secondary accession number(s): Q2TA96 , Q69ZK8, Q8C024, Q8K123, Q9CTP5, Q9D601

Entry history

Integrated into UniProtKB/Swiss-Prot:	May 30, 2000
Last sequence update:	April 5, 2011
Last modified:	May 1, 2013
This is version 118 of the entry and version 2 of the sequence. [Complete history]

Entry status

Reviewed (UniProtKB/Swiss-Prot)

Annotation program

Chordata Protein Annotation Program