• GPIb-beta
• GPIbb

MAJOR LINKS FOR CD42c  

• NCBI LocusLink Record: 2812
• Mendelian Inheritance in Man (OMIM): 138720
• SwissProt annotated protein record: P13224

• The CD42a-d-complex serves as receptor for von Willebrand factor (vWf) and thrombin
• The actual binding site for vWf and thrombin lies on CD42b (GPIb alpha)

CELLULAR FUNCTION OF CD42c  

• The complex mediates adhesion of platelets to subendothelial matrices (exposed upon damage to the endothelium) at high shear rates
• It also amplifies the platelet response to thrombin during platelet activation where thrombin is involved
• Phosphorylation of the Ser-166 in CD42c may regulate cytoskeleton interactions in platelets

DISEASE RELEVANCE OF CD42c AND FUNCTION OF CD42c IN INTACT ANIMAL  

• The Bernard-Soulier syndrome (BSS)(a bleeding disorder with the presence of giant platelets) is characterized by the absence of the GPIb/IX/V (CD42a-d) complex, so far mutations have been found in the genes encoding CD42a, CD42b and CD42c in patients with BSS**

• Families in which CD42c is a member
  • CD42c-->platelet-derived growth factor-->PTK-->protein kinase-->kinases

MOLECULAR STRUCTURE OF CD42c  

• Heterodimer composed of an alpha chain (CD42b) and a beta chain (CD42c) linked by a disulfide bond
• It forms a non-covalent linked complex with CD42a and d
• NH2-terminal extracytoplasmic region of approximately 122 amino acids, a transmembrane segment of approximately 25 amino acids and an intracellular region of 34 amino acids
• The extracellular region contains one tandem leucine-rich glycoprotein repeat sequence of 24 amino acids, flanked by consensus flanking sequences of 22 amino acids

MOLECULAR MASS OF CD42c  

POST-TRANSCRIPTIONAL MODIFICATION OF CD42c   - No information

POST-TRANSLATIONAL MODIFICATION OF CD42c  

• There is one potential N-glycosylation site
• Acylation, primarily palmitoylation, of GPIb has been found
• There is a phosphorylation site at Ser166, which can be phosphorylated by cAMP dependent protein kinase

SUBSTRATES FOR CD42c   - No information

ENZYMES WHICH MODIFY CD42c  

LIGANDS FOR CD42c AND MOLECULES ASSOCIATED WITH CD42c  

• Expression restricted to platelets and megakaryocytes

SELECTION OF OTHER CD42c-SPECIFIC REFERENCE MAB  

REVIEWS

PRIMARY CITATIONS

1. Clemetson KJ, McGregor JL, James E, Dechavanne M and Luscher EF. Characterization of the platelet membrane glycoprotein abnormalities in Bernard-Soulier syndrome and comparison with normal by surface-labeling techniques and high-resolution two-dimensional gel electrophoresis. J. Clin. Invest. 1982 70:304 PubMed

2. Fox JE, Aggerbeck LP and Berndt MC. Structure of the glycoprotein Ib.IX complex from platelet membranes. J. Biol. Chem. 1988 263:4882 PubMed

3. Kunishima S, Lopez JA, Kobayashi S, Imai N, Kamiya T, Saito H and Naoe T. Missense mutations of the glycoprotein (GP) Ib beta gene impairing the GPIb alpha/beta disulfide linkage in a family with giant platelet disorder. Blood 1997 89:2404 PubMed

4. Lopez JA, Chung DW, Fujikawa K, Hagen FS, Davie EW and Roth GJ. The alpha and beta chains of human platelet glycoprotein Ib are both transmembrane proteins containing a leucine-rich amino acid sequence. Proc. Natl. Acad. Sci. U.S.A. 1988 85:2135 PubMed

5. Ludlow LB, Schick BP, Budarf ML, Driscoll DA, Zackai EH, Cohen A and Konkle BA. Identification of a mutation in a GATA binding site of the platelet glycoprotein Ibbeta promoter resulting in the Bernard-Soulier syndrome. J. Biol. Chem. 1996 271:22076 PubMed

6. Muszbek L and Laposata M. Glycoprotein Ib and glycoprotein IX in human platelets are acylated with palmitic acid through thioester linkages. J. Biol. Chem. 1989 264:9716 PubMed

7. Nurden AT, Dupuis D, Kunicki TJ and Caen JP. Analysis of the glycoprotein and protein composition of Bernard-Soulier platelets by single and two-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis. J. Clin. Invest. 1981 67:1431 PubMed

8. Schick PK and Walker J. The acylation of megakaryocyte proteins: glycoprotein IX is primarily myristoylated while glycoprotein Ib is palmitoylated. Blood 1996 87:1377 PubMed

WWW RESOURCES

Portions copyright by Garland Press and by the International Workshops on Human Leukocyte Differentiation Antigens; used with permission

Modified 10/14/99   mpr@mail.nih.gov