Demonstration by phase-partitioning in Triton X-114 solutions that phosphoprotein B-50 (F-1) from rat brain is an integral membrane protein.
The Triton X-114 phase separation technique was employed to fractionate phosphoproteins present in membrane fragments from rat brain. Membranes were labelled with [gamma-32P]ATP in media containing Ca2+, Ca2+ plus calmodulin or cyclic AMP, and then treated with Triton X-114. Phosphoproteins recovered in the detergent-insoluble fraction, aqueous and detergent phases were detected by SDS-polyacrylamide gel electrophoresis and autoradiography. Of the proteins solubilised by the detergent, a known substrate of protein kinase C, the B-50 phosphoprotein (45 kD; also known as F-1), partitioned quantitatively into the detergent-rich phase, making it very probable that this phosphoprotein is an integral membrane protein. The detergent-rich phase also contained an 80 kD phosphoprotein, which probably corresponds to the widespread acidic 87 kD substrate of protein kinase C.
D000818:Animals; D001923:Brain Chemistry; D019922:GAP-43 Protein; D008565:Membrane Proteins / Q000032:analysis*; D017830:Octoxynol; D010750:Phosphoproteins / Q000032:analysis*; D011092:Polyethylene Glycols; D011493:Protein Kinase C; D051381:Rats; D012996:Solutions; D013379:Substrate Specificity; D013570:Synaptic Membranes / Q000032:analysis*
D019922:GAP-43 Protein; D008565:Membrane Proteins; D010750:Phosphoproteins; D012996:Solutions; D011092:Polyethylene Glycols; D017830:Octoxynol; C010615:Nonidet P-40; D011493:Protein Kinase C