Deletions in the N-terminal coding region of the v-sis gene: determination of the minimal transforming region.
The gene product of the v-sis gene is closely related to the B chain of platelet-derived growth factor (PDGF). However, v-sis also encodes additional amino acids at its N and C termini, which are not represented in the sequence data of PDGF. We have constructed a series of N-terminal deletion mutants in the v-sis gene to define the minimum region required for transformation. These mutants were assayed for biological activity by using retroviral expression vectors which donate a signal sequence, required for translocation across the rough endoplasmic reticulum, to the mutant gene product. The minimal transforming region of the v-sis gene product defined by this analysis has 15 residues missing at the N terminus when compared with the PDGF-B chain. There are only two residues separating the closest transforming and nontransforming gene products. Mutant gene products lacking both the basic dipeptide processing site and the N-linked glycosylation site were found to be biologically active, indicating the dispensability of those processing steps. These results delimit the minimal transforming region of the v-sis gene product to residues 127 through 214, a total of 21 residues smaller than the PDGF-B chain.
D000818:Animals; D002460:Cell Line; D002472:Cell Transformation, Viral; D002522:Chlorocebus aethiops; D002872:Chromosome Deletion; D003001:Cloning, Molecular; D005786:Gene Expression Regulation; D005822:Genetic Vectors; D006023:Glycoproteins / Q000235:genetics; D007158:Immunologic Techniques; D046911:Macromolecular Substances; D051379:Mice; D008970:Molecular Weight; D009856:Oncogene Proteins, Viral / Q000235:genetics* / Q000276:immunology; D011499:Protein Processing, Post-Translational; D011519:Proto-Oncogenes; D013997:Time Factors
D006023:Glycoproteins; D046911:Macromolecular Substances; D009856:Oncogene Proteins, Viral