Sphingosine activation of protein kinases in Jurkat T cells. In vitro phosphorylation of endogenous protein substrates and specificity of action.

摘要: Sphingosine displays multiple biochemical and biological effects, in particular inhibition activation of protein kinases. To determine the predominant interaction sphingosine with cellular kinases, effects on endogenous phosphorylation Jurkat T lymphoblastic cells were investigated vitro. was found to cause prominent a number cytosolic proteins ranging molecular mass from 18 165 kDa. Phosphorylation calcium-independent. substrates increased response concentrations as low 10 microM peaked at 20-200 microM. Multiple lines evidence suggested that activated more than one kinase: 1) concentration dependence differed substrate substrate, 2) group required ATP phosphate donor, whereas second showed no preference between GTP, 3) some inhibited by heparin, other resistant. Activation these kinases demonstrated very specific requirement for D-erythro-sphingoid bases. DL-erythro-dihydrosphingosine partially active, DL-threo-dihydrosphingosine not. Other related molecules such stearylamine, sphingomyelin, C2-ceramide not active. Sphingosine-activated kinase(s) distinct kinase C, cyclic nucleotide-activated calcium-dependent These observations demonstrate existence sphingosine-activated high specificity D-erythro-sphingosine, suggesting physiologic regulation sphingosine.