In vivo phosphorylation of the lamin B receptor. Binding of lamin B to its nuclear membrane receptor is affected by phosphorylation.

Previous studies have shown that the nuclear envelope of avian erythrocytes contains a 58-kDa integral membrane protein (p58) which serves as a receptor for the karyoskeletal protein lamin B (Worman, J. H., Yuan, J., Blobel, G., and Georgatos, S. D. (1988) Proc. Natl. Acad. Sci. U. S. A. 85, 8531-8534). We now demonstrate that p58 is phosphorylated in vivo at serine residues and that its phosphorylation is stimulated by isoproterenol in a dose-dependent fashion. We further show that dephosphorylation of p58 reduces significantly its binding to lamin B. These data suggest that phosphorylation may constitute one of the major mechanisms regulating the lamina-nuclear membrane interactions.