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CD42b; platelet glycoprotein Ib alpha chain; glycoprotein Ibalpha; GP-Ib alpha; GPIb-alpha; GPIbA; antigen CD42b-alpha; human platelet antigen 2; HPA-2 (GP1BA)

Function: - subunit of platelet glycoprotein 1B - interacts with FLNB - glycocalicin (approximately extracellular part), is cleaved by calpain during platelet lysis Structure: - contains 6 LRR repeats (leucine-rich repeats) - binding sites for von Willebrand factor & thrombin are in the amino-terminal part of the molecule Compartment: membrane Polymorphism: - associated with platelet-specific alloantigen Siba; Siba(-) has Thr-161 & Siba(+) has Met-161 - polymorphisms arise from a variable number of tandem repeats (NNTR) 13-amino acid repeats of S-E-P-A-P-S-P-T-T-P-E-P-T in the mucin-like macroglycopeptide (Pro/Thr-rich) domain a) allele A contains four repeats starting at position 415 b) allele B contains three repeats c) allele C contains two repeats d) allele D contains one repeat Pathology: - allele B of is associated with susceptibility to nonarteritic anterior ischemic optic neuropathy - defects in GP1BA are a cause of a) Bernard-Soulier syndrome b) benign Mediterranean macrothrombocytopenia c) von Willebrand disease Laboratory: - HPA-2 type in blood

Specific

glycocalcin

General

CD42 leucine-rich repeat-containing protein (LRRC) phosphoprotein

Properties

SIZE: entity length = 626 aa MW = 69 kD COMPARTMENT: cellular membrane MOTIF: signal sequence {1-16} cysteine residue {C20} MODIFICATION: cysteine residue {C33} cysteine residue {C33} MODIFICATION: cysteine residue {C20} N-glycosylation site {N37} leucine-rich repeat SITE: 70-92 MOTIF: leucine residue (SEVERAL) leucine-rich repeat SITE: 93-117 MOTIF: leucine residue (SEVERAL) leucine-rich repeat SITE: 119-138 MOTIF: leucine residue (SEVERAL) leucine-rich repeat SITE: 139-162 MOTIF: leucine residue (SEVERAL) leucine-rich repeat SITE: 164-186 MOTIF: leucine residue (SEVERAL) N-glycosylation site {N175} leucine-rich repeat SITE: 188-210 MOTIF: leucine residue (SEVERAL) cysteine residue {C225} MODIFICATION: cysteine residue {C264} cysteine residue {C227} MODIFICATION: cysteine residue {C280} cysteine residue {C264} MODIFICATION: cysteine residue {C225} cysteine residue {C280} MODIFICATION: cysteine residue {C227} Tyr phosphorylation site {Y292} Tyr phosphorylation site {Y294} Tyr phosphorylation site {Y295} Thr glycosylation site {T308} threonine-rich region {345-456} MOTIF: threonine residue (SEVERAL) transmembrane domain {506-526} Ser phosphorylation site {S603} Ser phosphorylation site {S606}

Database Correlations

OMIM correlations MORBIDMAP 606672 UniProt P07359 PFAM correlations Kegg hsa:2811

References

  1. UniProt :accession P07359
  2. GeneReviews https://www.genecards.org/cgi-bin/carddisp.pl?gene=GP1BA
  3. SeattleSNPs http://pga.gs.washington.edu/data/gp1ba/
  4. http://www.pathologyoutlines.com/cdmarkers.html 15 October 2002

Component-of

platelet glycoprotein 1b