plasma-membrane fractions fi and fii isolated from bovine corpus luteum by discontinuous sucrose-density-gradient centrifugation , at sucrose-density interfaces of 1.14/1.16 and 1.16/1.18 respectively , contained membrane-associated protein kinases that phosphorylated both the structural proteins of membranes as well as exogenously added protein substrates .
C0025252
membrane
C0033684
protein