Amino acid sequences in fibrinogen mediating its interaction with its platelet receptor, GPIIbIIIa.
Platelet membrane GPIIbIIIa is a member of the family receptors named integrins that recognize RGD sequences in their ligands. GPIIbIIIa interacts with at least three different adhesive ligands: fibrinogen, fibronectin, and von Willebrand factor. These interactions are inhibited by RGD-containing peptides and by peptides corresponding to a sequence unique to fibrinogen in the COOH-terminal domain of its gamma chain (HLGGAKQAGDV). Two RGD sequences are present in fibrinogen A alpha chain: an RGDS sequence at A alpha 572-575, and an RGDF sequence at A alpha 95-98. Polyclonal antibodies raised against the RGDF sequence and the gamma COOH-terminal domain both reacted specifically with fibrinogen in solid phase enzyme-linked immunosorbent assays and immunoprecipitated the protein in solution. The Fab fragments prepared from these antibodies inhibited fibrinogen-platelet interaction and aggregation. These results demonstrate that these two sequences are both accessible within the fibrinogen molecule and are both implicated in ligand binding and cell-cell interaction. In addition, by further examining the interaction of the gamma chain peptide with platelets, it was found that RGDF and the gamma peptide produced a similar dose-dependent inhibition of the binding of the labeled gamma peptide to ADP-stimulated platelets. These results provide evidence that the RGDF sequence present at the A alpha 95-98 constitutes with the gamma 401-411 sequence two recognition sites interacting with the same site or with mutually exclusive sites on GPIIbIIIa.
Andrieux
A
A
Département de Recherche Fondamentale, Inserm U217, Grenoble, France.
Hudry-Clergeon
G
G
Ryckewaert
J J
JJ
Chapel
A
A
Ginsberg
M H
MH
Plow
E F
EF
Marguerie
G
G
D000595:Amino Acid Sequence; D000818:Animals; D000906:Antibodies / Q000502:physiology; D000918:Antibody Specificity; D005340:Fibrinogen / Q000276:immunology / Q000378:metabolism / Q000502:physiology*; D006801:Humans; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000502:physiology; D010975:Platelet Aggregation Inhibitors / Q000502:physiology; D010980:Platelet Membrane Glycoproteins / Q000378:metabolism / Q000502:physiology*; D051381:Rats; D011971:Receptors, Immunologic / Q000502:physiology*; D018000:Receptors, Peptide; D012689:Sequence Homology, Nucleic Acid
D000906:Antibodies; D010446:Peptide Fragments; D010975:Platelet Aggregation Inhibitors; D010980:Platelet Membrane Glycoproteins; D011971:Receptors, Immunologic; D018000:Receptors, Peptide; C051382:arginyl-glycyl-aspartic acid directed cell adhesion receptor; D005340:Fibrinogen