Occupancy of an adhesive glycoprotein receptor modulates expression of an antigenic site involved in cell adhesion.
Binding of ligands that contain Arg-Gly-Asp to adhesion receptors induces cell spreading and aggregation and alters gene expression, possibly due to conformational changes within occupied adhesion receptors. PMI-1 is a monoclonal antibody which reacts with the platelet fibrinogen receptor, glycoprotein IIb-IIIa, and reports such a conformational change. ADP stimulation of platelets results in a fibrinogen-dependent increase in binding of the PMI-1 antibody. Peptides containing Arg-Gly-Asp also reversibly increase the binding of this antibody to cells and to purified glycoprotein IIb-IIIa. The PMI-1 antibody inhibits platelet adhesion and spreading on certain substrata (Shadle, P. J., Ginsberg, M. H., Plow, E. F., and Barondes, S. H. (1984) J. Cell Biol. 99, 2056-2060); thus this occupancy-modulated site may participate in adhesive function.
Frelinger
A L
AL
Department of Immunology, Research Institute of Scripps Clinic, La Jolla, California 92037.
Lam
S C
SC
Plow
E F
EF
Smith
M A
MA
Loftus
J C
JC
Ginsberg
M H
MH
D000244:Adenosine Diphosphate / Q000494:pharmacology; D000911:Antibodies, Monoclonal / Q000276:immunology / Q000502:physiology*; D001792:Blood Platelets / Q000502:physiology*; D002118:Calcium / Q000494:pharmacology; D002413:Cations, Divalent; D004492:Edetic Acid / Q000494:pharmacology; D004797:Enzyme-Linked Immunosorbent Assay; D000939:Epitopes / Q000276:immunology*; D005340:Fibrinogen / Q000494:pharmacology; D006801:Humans; D009842:Oligopeptides / Q000494:pharmacology; D010455:Peptides / Q000494:pharmacology; D010973:Platelet Adhesiveness; D010980:Platelet Membrane Glycoproteins / Q000276:immunology / Q000502:physiology*; D011487:Protein Conformation; D011971:Receptors, Immunologic / Q000276:immunology / Q000502:physiology*; D018000:Receptors, Peptide
D000911:Antibodies, Monoclonal; D002413:Cations, Divalent; D000939:Epitopes; D009842:Oligopeptides; D010455:Peptides; D010980:Platelet Membrane Glycoproteins; D011971:Receptors, Immunologic; D018000:Receptors, Peptide; C051382:arginyl-glycyl-aspartic acid directed cell adhesion receptor; D000244:Adenosine Diphosphate; C047981:arginyl-glycyl-aspartic acid; D005340:Fibrinogen; D004492:Edetic Acid; D002118:Calcium