Type-specific antibodies to the platelet-derived growth factor receptors: role in elucidating the structural and functional characteristics of receptor types.
Two types of platelet-derived growth factor receptors have been cloned and sequenced. Both are glycoproteins with similar molecular weights. We have earlier established the ligand binding specificity, ligand-induced dimerization, and kinase activation of these two receptor types [Bishayee et al. (1989) J. Biol. Chem. 264, 11699-11705; Kanakaraj et al. (1991) Biochemistry 30, 1761-1767]. In the present studies, we have investigated the biosynthesis, processing, and glycosylation of the alpha-receptor and compared its structural and functional characteristics to those of the beta-receptor. Unlike an anti-peptide antibody, AbP2 (amino acid residues 964-979), to the human beta-receptor which detects a phosphorylation-specific conformation of the receptor, an antibody, AbP alpha 2 (amino acid residues 956-971), to the corresponding region of the human alpha-receptor failed to do so. However, our studies revealed that the stability of the alpha-receptor is comparable to that of the beta-receptor. In addition, N-linked glycosylation of the alpha-receptor, like that of the beta-receptor, is not important in kinase activation. We have exploited the lack of an effect of N-linked oligosaccharides on the functioning of the alpha-receptor to develop a simple and rapid method for direct demonstration of ligand-induced noncovalently linked alpha-beta-receptor heterodimer formation. This method is based on the interaction between functionally active short and the long forms of two receptor types which can be resolved by denaturing gel electrophoresis.
Raj
S
S
Coriell Institute for Medical Research, Camden, New Jersey 08103.
Kanakaraj
P
P
Khan
S A
SA
Bishayee
S
S
D000595:Amino Acid Sequence; D000906:Antibodies / Q000276:immunology*; D000918:Antibody Specificity; D001254:Astrocytoma; D015153:Blotting, Western; D000939:Epitopes / Q000276:immunology; D006031:Glycosylation; D006801:Humans; D007163:Immunosorbent Techniques; D046911:Macromolecular Substances; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry / Q000276:immunology; D010766:Phosphorylation; D011487:Protein Conformation; D011956:Receptors, Cell Surface / Q000737:chemistry* / Q000276:immunology / Q000502:physiology; D017479:Receptors, Platelet-Derived Growth Factor; D014407:Tumor Cells, Cultured; D014415:Tunicamycin / Q000494:pharmacology
D000906:Antibodies; D000939:Epitopes; D046911:Macromolecular Substances; D010446:Peptide Fragments; D011956:Receptors, Cell Surface; D014415:Tunicamycin; D017479:Receptors, Platelet-Derived Growth Factor