Reviewed, UniProtKB/Swiss-Prot Q06077 (ABRB_ABRPR)

Names and origin

Protein names	Recommended name:     Abrin-b Cleaved into the following 3 chains:     1- Recommended name:             Abrin-b A chain               EC=3.2.2.22         Alternative name(s):             rRNA N-glycosidase     2- Recommended name:             Linker peptide     3- Recommended name:             Abrin-b B chain
Organism	Abrus precatorius (Indian licorice) (Crab's eye)
Taxonomic identifier	3816 [NCBI]
Taxonomic lineage	Eukaryota › Viridiplantae › Streptophyta › Embryophyta › Tracheophyta › Spermatophyta › Magnoliophyta › eudicotyledons › core eudicotyledons › rosids › eurosids I › Fabales › Fabaceae › Papilionoideae › Abreae › Abrus

Protein attributes

Sequence length	527 AA.
Sequence status	Complete.
Sequence processing	The displayed sequence is further processed into a mature form.
Protein existence	Evidence at protein level.

General annotation (Comments)

Function	The a chain is responsible for inhibiting protein synthesis through the catalytic inactivation of 60S ribosomal subunits by removing adenine from position 4,324 of 28S rRNA. Abrin-a is more toxic than ricin. The B chain is a galactose-specific lectin that facilitates the binding of abrin to the cell membrane that precedes endocytosis.
Catalytic activity	Endohydrolysis of the N-glycosidic bond at one specific adenosine on the 28S rRNA.
Subunit structure	Disulfide-linked dimer of A and B chains.
Domain	The B chain is composed of two domains, each domain consists of 3 homologous subdomains (alpha, beta, gamma).
Sequence similarities	In the N-terminal section; belongs to the ribosome-inactivating protein family. Type 2 RIP subfamily. Contains 2 ricin B-type lectin domains.

Ontologies

Keywords
Biological process	Plant defense
Domain	Repeat
Ligand	Lectin
Molecular function	Hydrolase Protein synthesis inhibitor Toxin
PTM	Disulfide bond Glycoprotein Pyrrolidone carboxylic acid
Technical term	Direct protein sequencing
Gene Ontology (GO)
Biological process	defense response Inferred from electronic annotation. Source: UniProtKB-KW negative regulation of translation Inferred from electronic annotation. Source: UniProtKB-KW pathogenesis Inferred from electronic annotation. Source: UniProtKB-KW
Molecular function	rRNA N-glycosylase activity Inferred from electronic annotation. Source: EC sugar binding Inferred from electronic annotation. Source: UniProtKB-KW
Complete GO annotation...

Sequence annotation (Features)

	Feature key	Position(s)	Length	Description	Graphical view	Feature identifier
Molecule processing
	Chain	1 – 250	250	Abrin-b A chain		PRO_0000030732
	Peptide	251 – 260	10	Linker peptide		PRO_0000030733
	Chain	261 – 527	267	Abrin-b B chain		PRO_0000030734
Regions
	Domain	272 – 399	128	Ricin B-type lectin 1
	Repeat	282 – 324	43	1-alpha
	Repeat	325 – 365	41	1-beta
	Repeat	368 – 400	33	1-gamma
	Domain	402 – 526	125	Ricin B-type lectin 2
	Repeat	413 – 448	36	2-alpha
	Repeat	452 – 491	40	2-beta
	Repeat	494 – 527	34	2-gamma
Sites
	Active site	163	1	By similarity
Amino acid modifications
	Modified residue	1	1	Pyrrolidone carboxylic acid By similarity
	Glycosylation	110	1	N-linked (GlcNAc...) Potential
	Glycosylation	360	1	N-linked (GlcNAc...) Potential
	Glycosylation	400	1	N-linked (GlcNAc...) Potential
	Disulfide bond	246 ↔ 268		Interchain (between A and B chains) By similarity
	Disulfide bond	285 ↔ 304		By similarity
	Disulfide bond	328 ↔ 345		By similarity
	Disulfide bond	416 ↔ 429		By similarity
	Disulfide bond	455 ↔ 472		By similarity
Experimental info
	Sequence conflict	282	1	N → D AA sequence Ref.2
	Sequence conflict	291	1	D → N AA sequence Ref.2
	Sequence conflict	350 – 351	2	AE → PQ AA sequence Ref.2
	Sequence conflict	378	1	S → N AA sequence Ref.2
	Sequence conflict	426	1	L → M AA sequence Ref.2
	Sequence conflict	428	1	Y → D AA sequence Ref.2
	Sequence conflict	431	1	N → S AA sequence Ref.2
	Sequence conflict	484	1	R → K AA sequence Ref.2
	Sequence conflict	491	1	N → S AA sequence Ref.2
	Sequence conflict	493	1	H → Y AA sequence Ref.2
	Sequence conflict	502	1	R → G AA sequence Ref.2
	Sequence conflict	509	1	E → Q AA sequence Ref.2
	Sequence conflict	513	1	H → W AA sequence Ref.2
	Sequence conflict	516	1	H → T AA sequence Ref.2

Sequences

	Sequence		Length	Mass (Da)
	Q06077-1 [UniParc]. Last modified November 1, 1996. Version 1. Checksum: 3253AE490CE9494A	FASTA	527	59,115
	10 20 30 40 50 60 QDQVIKFTTE GATSQSYKQF IEALRQRLTG GLIHGIPVLP DPTTLQERNR YISVELSNSD 70 80 90 100 110 120 TESIEAGIDV SNAYVVAYRA GNRSYFLRDA PTSASRYLFT GTQQYSLRFN GSYIDLERLA 130 140 150 160 170 180 RQTRQQIPLG LQALRHAISF LQSGTDDQEI ARTLIVIIQM ASEAARYRFI SYRVGVSIRT 190 200 210 220 230 240 NTAFQPDAAM ISLENNWDNL SGGVQQSVQD TFPNAVTLRS VNNQPVIVDS LTHQSVAVLA 250 260 270 280 290 300 LMLFVCNPPN ANQSPLLIRS IVEKSKICSS RYEPTVRIGG RNGMCVDVYD DGYHNGNRII 310 320 330 340 350 360 AWKCKDRLEE NQLWTLKSDK TIRSNGKCLT TEGYAPGNYV MIYDCTSAVA EATYWEIWDN 370 380 390 400 410 420 GTIINPKSAL VLSAESSSMG GTLTVQTNEY LMRQGWRTGN NTSPFVTSIS GYSDLCMQAQ 430 440 450 460 470 480 GSNVWLAYCD NNKKEQQWAL YTDGSIRSVQ NTNNCLTSKD HKQGSPIVLM ACSNGWASQR 490 500 510 520 WLFRNDGSIY NLHDDMVMDV KRSDPSLKEI ILHPYHGKPN QIWLTLF

References

[1]	"Primary structure of three distinct isoabrins determined by cDNA sequencing. Conservation and significance." Hung C.-H., Lee M.-C., Lee T.-C., Lin J.-Y. J. Mol. Biol. 229:263-267(1993) [PubMed: 8421313] [Abstract] Cited for: NUCLEOTIDE SEQUENCE [MRNA].
[2]	"The complete amino acid sequences of the B-chains of abrin-a and abrin-b, toxic proteins from the seeds of Abrus precatorius." Kimura M., Sumizawa T., Funatsu G. Biosci. Biotechnol. Biochem. 57:166-169(1993) [PubMed: 7763422] [Abstract] Cited for: PROTEIN SEQUENCE OF 260-527. Tissue: Seed.

Cross-references

Sequence databases
EMBLGenBankDDBJ	M98345 mRNA. Translation: AAA32625.1.
PIR	S32430.
3D structure databases
HSSP	HSSP built from PDB template 1ABR based on UniProtKB P11140.
SMR	Q06077. Positions 1-250, 261-527.
ModBase	Search...
Enzyme and pathway databases
BRENDA	3.2.2.22. 273549.
Family and domain databases
InterPro	IPR001574. Ribosome_inactivat_prot. IPR017988. Ribosome_inactivat_prot_CS. IPR016138. Ribosome_inactivat_prot_sub1. IPR016139. Ribosome_inactivat_prot_sub2. IPR017989. Ribosome_inactivat_prot_subgr. IPR000772. Ricin_B_lectin. [Graphical view]
Gene3D	G3DSA:3.40.420.10. Ribosome_inactivat_prot_sub1. 1 hit. G3DSA:4.10.470.10. Ribosome_inactivat_prot_sub2. 1 hit.
Pfam	PF00652. Ricin_B_lectin. 2 hits. PF00161. RIP. 1 hit. [Graphical view]
PRINTS	PR00396. SHIGARICIN.
SMART	SM00458. RICIN. 2 hits. [Graphical view]
PROSITE	PS50231. RICIN_B_LECTIN. 2 hits. PS00275. SHIGA_RICIN. 1 hit. [Graphical view]
ProtoNet	Search...

Entry information

Entry name

ABRB_ABRPR

Accession

Primary (citable) accession number: Q06077
Secondary accession number(s): P81374

Entry history

Integrated into UniProtKB/Swiss-Prot:	December 15, 1998
Last sequence update:	November 1, 1996
Last modified:	June 16, 2009
This is version 68 of the entry and version 1 of the sequence. [Complete history]

Entry status

Reviewed (UniProtKB/Swiss-Prot)

Annotation project

PPAP (Plant Proteome Annotation Project)