Biosynthesis and processing of the platelet derived growth factor type alpha receptor

The homodimers (AA, BB) of the platelet derived growth factor (PDGF) differentially interact with two highly related PDGF receptors (alpha, beta) that appear to mediate different functional responses in different cell types. To seek a basis for these apparent functional differences, we investigated the processing of the PDGF alpha-receptor. The PDGF alpha-receptor is rapidly glycosylated to a 160 kD form and undergoes a number of intermediate glycosylation steps that result in a mature form of 185 kD that appears at the cell surface within 60-90 minutes. The alpha receptor has a half-life of approximately 4 1/2 hours without and approximately 20 minutes in the presence of ligand. The processing steps of the alpha-receptor are similar to the processing of the PDGF beta receptor, suggesting that differential binding of signalling molecules to activated receptors may be responsible for the apparent functional differences in cellular responses to PDGF AA and PDGF BB.