Dioctanoylglycerol and phorbol diesters enhance phosphorylation of phosphoprotein B-50 in native synaptic plasma membranes.
The short chain diacylglycerol, 1,2-dioctanoylglycerol, at concentrations of 100-300 microM stimulated phosphorylation of the nervous system-specific membrane protein B-50 (Mr 48 kDa, IEP 4.5) in isolated synaptic plasma membranes both in the presence and absence of exogenous protein kinase C. Comparable enhancement of histone phosphorylation by purified protein kinase C was achieved with 1 microM neutral lipid. Phorbol dibutyrate was 100 times more potent than the diacylglycerol in stimulating endogenous B-50 kinase in the membranes, whereas 4-alpha-phorbol was without effect. These results further confirm that B-50 is phosphorylated physiologically by a C kinase. Our data are consistent with a negative feedback mechanism in which generation of 1,2-diacylglycerol by enhanced phosphatidylinositol-4,5-bisphosphate hydrolysis could stimulate B-50 phosphorylation, thereby diminishing phosphatidylinositol-4-phosphate kinase activity and decreasing phosphatidylinositol-4,5-bisphosphate biosynthesis.
D000818:Animals; D002118:Calcium / Q000378:metabolism; D004075:Diglycerides / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D019922:GAP-43 Protein; D005989:Glycerides / Q000494:pharmacology*; D006657:Histones / Q000378:metabolism; D015240:Phorbol 12,13-Dibutyrate; D010703:Phorbol Esters / Q000494:pharmacology*; D010704:Phorbols / Q000494:pharmacology; D010750:Phosphoproteins / Q000378:metabolism*; D010766:Phosphorylation; D011493:Protein Kinase C / Q000378:metabolism; D051381:Rats; D013570:Synaptic Membranes / Q000187:drug effects / Q000378:metabolism*
D004075:Diglycerides; D019922:GAP-43 Protein; D005989:Glycerides; D006657:Histones; D010703:Phorbol Esters; D010704:Phorbols; D010750:Phosphoproteins; C044295:1,2-dioctanoylglycerol; D015240:Phorbol 12,13-Dibutyrate; D011493:Protein Kinase C; D002118:Calcium; C033085:phorbol