The cellular src gene product regulates junctional cell-to-cell communication

Overexpression of the cellular src gene in NIH 3T3 cells causes reduction of cell-to-cell transmission of molecules in the 400- to 700-dalton range. This down-regulation of gap junctional communication correlates with the activity of the gene product, the protein tyrosine kinase pp60. The down-regulation was enhanced by point mutation of Tyr (a site that is phosphorylated in pp60 and diat inhibits kinase activity) or by substitution of the viral-src for the cellular-src carboxyl-terminal coding region. Mutation of Tyr (a site phosphorylated upon Tyr mutation) suppresses both the down-regulation of communication by Tyr mutation and that by gene overexpression. The regulation of communication by src may be important in the control of embryonic development and cellular growth.