P08334 (LALB1_HORSE) Reviewed, UniProtKB/Swiss-Prot

Names and origin

Protein names	Recommended name: Alpha-lactalbumin A Alternative name(s): Lactose synthase B protein
Organism	Equus caballus (Horse) [Reference proteome]
Taxonomic identifier	9796 [NCBI]
Taxonomic lineage	cellular organisms › Eukaryota › Opisthokonta › Metazoa › Eumetazoa › Bilateria › Deuterostomia › Chordata › Craniata › Vertebrata › Gnathostomata › Teleostomi › Euteleostomi › Sarcopterygii › Tetrapoda › Amniota › Mammalia › Theria › Eutheria › Laurasiatheria › Perissodactyla › Equidae › Equus › Equus

Protein attributes

Sequence length	123 AA.
Sequence status	Complete.
Protein existence	Evidence at protein level

General annotation (Comments)

Function	Regulatory subunit of lactose synthase, changes the substrate specificity of galactosyltransferase in the mammary gland making glucose a good acceptor substrate for this enzyme. This enables LS to synthesize lactose, the major carbohydrate component of milk. In other tissues, galactosyltransferase transfers galactose onto the N-acetylglucosamine of the oligosaccharide chains in glycoproteins.
Subunit structure	Lactose synthase (LS) is a heterodimer of a catalytic component, beta1,4-galactosyltransferase (beta4Gal-T1) and a regulatory component, alpha-lactalbumin (LA).
Subcellular location	Secreted.
Tissue specificity	Mammary gland specific. Secreted in milk.
Sequence similarities	Belongs to the glycosyl hydrolase 22 family.

Ontologies

Keywords
Biological process	Lactose biosynthesis
Cellular component	Secreted
Ligand	Calcium Metal-binding
Molecular function	Milk protein
PTM	Disulfide bond
Technical term	Complete proteome Direct protein sequencing Reference proteome
Gene Ontology (GO)
Biological_process	lactose biosynthetic process Inferred from electronic annotation. Source: UniProtKB-KW
Cellular_component	extracellular region Inferred from electronic annotation. Source: UniProtKB-SubCell
Molecular_function	calcium ion binding Inferred from electronic annotation. Source: InterPro lactose synthase activity Inferred from electronic annotation. Source: InterPro
Complete GO annotation...

Sequence annotation (Features)

	Feature key	Position(s)	Length	Description	Graphical view	Feature identifier
Molecule processing
	Chain	1 – 123	123	Alpha-lactalbumin A		PRO_0000208836
Regions
	Calcium binding	78 – 89	12	By similarity
Amino acid modifications
	Disulfide bond	6 ↔ 120		By similarity
	Disulfide bond	28 ↔ 111		By similarity
	Disulfide bond	61 ↔ 77		By similarity
	Disulfide bond	73 ↔ 91		By similarity

Sequences

	Sequence		Length	Mass (Da)
	P08334 [UniParc]. Last modified October 1, 1989. Version 2. Checksum: A1780DE55B7C4864	FASTA	123	14,223
	10 20 30 40 50 60 KQFTKCELSQ VLKSMDGYKG VTLPEWICTI FHSSGYDTQT IVKNNGKTEY GLFQINNKMW 70 80 90 100 110 120 CRDNQILPSR NICGISCDKF LDDDLTDDVM CAKKILDSEG IDYWLAHKPL CSEKLEQWLC EEL

References

[1]	"The amino acid sequence of equine alpha-lactalbumin." Kaminogawa S., McKenzie H.A., Shaw D.C. Biochem. Int. 9:539-546(1984) [PubMed] [Europe PMC] [Abstract] Cited for: PROTEIN SEQUENCE.
[2]	"Identification and the primary structure of equine alpha-lactalbumin B and C (Equus caballus, Perissodactyla)." Godovac-Zimmermann J., Shaw D., Conti A., McKenzie H.A. Biol. Chem. Hoppe-Seyler 368:427-433(1987) [PubMed] [Europe PMC] [Abstract] Cited for: SEQUENCE REVISION TO 10.

Cross-references

Sequence databases
PIR	LAHO. A29147.
3D structure databases
ProteinModelPortal	P08334.
SMR	P08334. Positions 1-123.
ModBase	Search...
Protein-protein interaction databases
STRING	9796.ENSECAP00000001776.
Protein family/group databases
Allergome	1498. Equ c ALA.
Protocols and materials databases
StructuralBiologyKnowledgebase	Search...
Phylogenomic databases
eggNOG	NOG72593.
HOGENOM	HOG000037357.
HOVERGEN	HBG052297.
InParanoid	P08334.
OrthoDB	EOG43JC60.
Family and domain databases
InterPro	IPR001916. Glyco_hydro_22. IPR019799. Glyco_hydro_22_CS. IPR000545. Lactalbumin. IPR023346. Lysozyme-like_dom. [Graphical view]
PANTHER	PTHR11407:SF5. PTHR11407:SF5. 1 hit.
Pfam	PF00062. Lys. 1 hit. [Graphical view]
PRINTS	PR00136. LACTALBUMIN. PR00135. LYZLACT.
SMART	SM00263. LYZ1. 1 hit. [Graphical view]
SUPFAM	SSF53955. SSF53955. 1 hit.
PROSITE	PS00128. LACTALBUMIN_LYSOZYME_1. 1 hit. PS51348. LACTALBUMIN_LYSOZYME_2. 1 hit. [Graphical view]
ProtoNet	Search...

Entry information

Entry name

LALB1_HORSE

Accession

Primary (citable) accession number: P08334

Entry history

Integrated into UniProtKB/Swiss-Prot:	August 1, 1988
Last sequence update:	October 1, 1989
Last modified:	April 3, 2013
This is version 79 of the entry and version 2 of the sequence. [Complete history]

Entry status

Reviewed (UniProtKB/Swiss-Prot)

Annotation program

Chordata Protein Annotation Program