ID   LALBA_MACGI             Reviewed;          42 AA.
AC   P19122;
DT   01-NOV-1990, integrated into UniProtKB/Swiss-Prot.
DT   01-NOV-1990, sequence version 1.
DT   25-MAY-2022, entry version 75.
DE   RecName: Full=Alpha-lactalbumin I;
DE   AltName: Full=Lactose synthase B protein;
DE   Flags: Fragment;
GN   Name=LALBA;
OS   Macropus giganteus (Eastern gray kangaroo).
OC   Eukaryota; Metazoa; Chordata; Craniata; Vertebrata; Euteleostomi; Mammalia;
OC   Metatheria; Diprotodontia; Macropodidae; Macropus.
OX   NCBI_TaxID=9317;
RN   [1]
RP   PROTEIN SEQUENCE.
RX   PubMed=4718741; DOI=10.1016/s0021-9258(19)43726-5;
RA   Brew K., Steinman H.M., Hill R.L.;
RT   "A partial amino acid sequence of alpha-lactalbumin-I of the grey kangaroo
RT   (Macropus giganteus).";
RL   J. Biol. Chem. 248:4739-4742(1973).
CC   -!- FUNCTION: Regulatory subunit of lactose synthase, changes the substrate
CC       specificity of galactosyltransferase in the mammary gland making
CC       glucose a good acceptor substrate for this enzyme. This enables LS to
CC       synthesize lactose, the major carbohydrate component of milk. In other
CC       tissues, galactosyltransferase transfers galactose onto the N-
CC       acetylglucosamine of the oligosaccharide chains in glycoproteins.
CC   -!- SUBUNIT: Lactose synthase (LS) is a heterodimer of a catalytic
CC       component, beta1,4-galactosyltransferase (beta4Gal-T1) and a regulatory
CC       component, alpha-lactalbumin (LA).
CC   -!- SUBCELLULAR LOCATION: Secreted.
CC   -!- TISSUE SPECIFICITY: Mammary gland specific. Secreted in milk.
CC   -!- SIMILARITY: Belongs to the glycosyl hydrolase 22 family.
CC       {ECO:0000255|PROSITE-ProRule:PRU00680}.
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DR   PIR; A10265; A10265.
DR   AlphaFoldDB; P19122; -.
DR   SMR; P19122; -.
DR   GO; GO:0005576; C:extracellular region; IEA:UniProtKB-SubCell.
DR   GO; GO:0005989; P:lactose biosynthetic process; IEA:UniProtKB-KW.
DR   InterPro; IPR001916; Glyco_hydro_22.
DR   InterPro; IPR023346; Lysozyme-like_dom_sf.
DR   Pfam; PF00062; Lys; 1.
DR   SUPFAM; SSF53955; SSF53955; 1.
DR   PROSITE; PS51348; GLYCOSYL_HYDROL_F22_2; 1.
PE   1: Evidence at protein level;
KW   Calcium; Direct protein sequencing; Lactose biosynthesis; Milk protein;
KW   Secreted.
FT   CHAIN           1..>42
FT                   /note="Alpha-lactalbumin I"
FT                   /id="PRO_0000208838"
FT   DOMAIN          1..>42
FT                   /note="C-type lysozyme"
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00680"
FT   NON_TER         42
SQ   SEQUENCE   42 AA;  4727 MW;  130703419A7E9876 CRC64;
     IDYRKCQASQ ILKEHGMDKV IPLPELVCTM FHISGLSPQA EV