ID   ANP3_PAGBO              Reviewed;          31 AA.
AC   P02732;
DT   21-JUL-1986, integrated into UniProtKB/Swiss-Prot.
DT   21-JUL-1986, sequence version 1.
DT   25-MAY-2022, entry version 54.
DE   RecName: Full=Ice-structuring glycoprotein 3;
DE            Short=ISGP 3;
DE   AltName: Full=Antifreeze glycoprotein 3;
DE   Flags: Fragments;
OS   Pagothenia borchgrevinki (Bald rockcod) (Trematomus borchgrevinki).
OC   Eukaryota; Metazoa; Chordata; Craniata; Vertebrata; Euteleostomi;
OC   Actinopterygii; Neopterygii; Teleostei; Neoteleostei; Acanthomorphata;
OC   Eupercaria; Perciformes; Notothenioidei; Nototheniidae; Pagothenia.
OX   NCBI_TaxID=8213;
RN   [1]
RP   PROTEIN SEQUENCE.
RX   PubMed=5542001; DOI=10.1016/s0021-9258(18)62492-5;
RA   Devries A.L., Vandenheede J., Feeney R.E.;
RT   "Primary structure of freezing point-depressing glycoproteins.";
RL   J. Biol. Chem. 246:305-308(1971).
RN   [2]
RP   PROTEIN SEQUENCE.
RX   PubMed=5006918; DOI=10.1016/0006-291x(72)90633-x;
RA   Lin Y., Duman J.G., Devries A.L.;
RT   "Studies on the structure and activity of low molecular weight
RT   glycoproteins from an antarctic fish.";
RL   Biochem. Biophys. Res. Commun. 46:87-92(1972).
CC   -!- FUNCTION: Antifreeze proteins lower the blood freezing point. This fish
CC       lives in antarctic waters where it experiences water temperatures near
CC       -1.9 degrees Celsius. Its blood has a freezing point of about -2.0
CC       degrees Celsius, and 30% of the freezing-point depression is due mainly
CC       to the 3 major high molecular weight glycoproteins in the plasma.
CC   -!- SUBCELLULAR LOCATION: Secreted.
CC   -!- PTM: O-linked glycans consist of Gal-GalNAc disaccharides. The three
CC       proteins may differ only in the number of repeating units of -Ala-Ala-
CC       Thr-.
CC   -!- MISCELLANEOUS: The two small glycopeptides are present in a much higher
CC       concentration (5 times by weight) than the HMW glycoproteins but
CC       produce only a small depression effect. The exact physiological role of
CC       the small glycopeptides is not known.
CC   -!- MISCELLANEOUS: The three major glycoproteins (3, 4, and 5) have the
CC       same N-terminal sequence, A-A-T-A-A-T, and C-terminal Ala. Each protein
CC       is composed only of Ala and Thr residues in a ratio of 2:1 and arranged
CC       in the repeating sequence -A-A-T-.
CC   -!- MISCELLANEOUS: The small glycopeptides 7 and 8 appear to contain 20 and
CC       14 residues, respectively, and to have the same N-terminal sequence and
CC       C-terminal residue as the 3 major proteins. However, each has 2 Pro
CC       residues (instead of 1 of the Ala in each of 2 repeating units).
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DR   PIR; A03191; A03191.
DR   AlphaFoldDB; P02732; -.
DR   iPTMnet; P02732; -.
DR   GO; GO:0005576; C:extracellular region; IEA:UniProtKB-SubCell.
PE   1: Evidence at protein level;
KW   Antifreeze protein; Direct protein sequencing; Glycoprotein; Repeat;
KW   Secreted.
FT   CHAIN           1..31
FT                   /note="Ice-structuring glycoprotein 3"
FT                   /id="PRO_0000155143"
FT   CARBOHYD        3
FT                   /note="O-linked (GalNAc...) threonine"
FT                   /evidence="ECO:0000269|PubMed:5542001"
FT   CARBOHYD        6
FT                   /note="O-linked (GalNAc...) threonine"
FT                   /evidence="ECO:0000269|PubMed:5542001"
FT   CARBOHYD        9
FT                   /note="O-linked (GalNAc...) threonine"
FT                   /evidence="ECO:0000269|PubMed:5542001"
FT   CARBOHYD        12
FT                   /note="O-linked (GalNAc...) threonine"
FT                   /evidence="ECO:0000269|PubMed:5542001"
FT   CARBOHYD        15
FT                   /note="O-linked (GalNAc...) threonine"
FT                   /evidence="ECO:0000269|PubMed:5542001"
FT   CARBOHYD        18
FT                   /note="O-linked (GalNAc...) threonine"
FT                   /evidence="ECO:0000269|PubMed:5542001"
FT   CARBOHYD        21
FT                   /note="O-linked (GalNAc...) threonine"
FT                   /evidence="ECO:0000269|PubMed:5542001"
FT   CARBOHYD        24
FT                   /note="O-linked (GalNAc...) threonine"
FT                   /evidence="ECO:0000269|PubMed:5542001"
FT   CARBOHYD        27
FT                   /note="O-linked (GalNAc...) threonine"
FT                   /evidence="ECO:0000269|PubMed:5542001"
FT   CARBOHYD        30
FT                   /note="O-linked (GalNAc...) threonine"
FT                   /evidence="ECO:0000269|PubMed:5542001"
FT   NON_CONS        30..31
FT                   /evidence="ECO:0000305"
SQ   SEQUENCE   31 AA;  2522 MW;  613109D78109D7D0 CRC64;
     AATAATAATA ATAATAATAA TAATAATAAT A