Reconstitution of the Rous sarcoma virus transforming protein pp60v-src into phospholipid vesicles.
An artificial membrane system was developed to study the molecular basis for interaction of pp60v-src, the Rous sarcoma virus transforming protein, with lipid bilayers. pp60v-src was extracted from cell membranes by detergent solubilization and reincorporated into phospholipid vesicles. Reconstituted pp60v-src retained tyrosine kinase activity and was integrally associated with the liposome through a 10-kilodalton (kDa) amino-terminal domain. The same 10-kDa domain was shown to anchor pp60v-src to the plasma membrane of transformed cells. Reconstitution experiments performed with nonmyristylated pp60v-src proteins revealed that these polypeptides did not interact with phospholipid vesicles. In contrast, myristylated, soluble pp60v-src molecules (including a highly purified pp60v-src preparation) could be reconstituted into liposomes, but their interaction with the liposomal bilayer was not mediated by the 10-kDa amino-terminal domain. When membrane proteins were included during reconstitution of purified pp60v-src, binding through the 10-kDa anchor was restored. A model is presented to accommodate the different types of interactions of pp60v-src with liposomes; the model postulates the existence of an additional membrane component that anchors the pp60v-src polypeptide to the phospholipid bilayer.
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MD
Department of Biology, Princeton University, New Jersey 08544.
D000818:Animals; D001358:Avian Sarcoma Viruses; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D002642:Chick Embryo; D005347:Fibroblasts / Q000032:analysis; D008081:Liposomes / Q000378:metabolism*; D008954:Models, Biological; D015688:Oncogene Protein pp60(v-src); D011485:Protein Binding; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D012191:Retroviridae Proteins / Q000378:metabolism*
D008081:Liposomes; D012191:Retroviridae Proteins; D011505:Protein-Tyrosine Kinases; D015688:Oncogene Protein pp60(v-src)