SUBCELLULAR-DISTRIBUTION OF THE R-SUBUNITS OF CAMP-DEPENDENT PROTEIN-KINASE IN LS-174T HUMAN COLON-CARCINOMA CELLS

The analysis of the particulate preparations of LS-174T human colon ca rcinoma cells in confluent stage of growth revealed different distribu tion for regulatory subunits (R) of cAMP-dependent protein kinase (PKA ) in the subcellular compartments. The LS-174T cell lysates were subje cted to differential and discontinuous sucrose density gradient centri fugation. The obtained fractions were assayed for marker enzymes and p hotoaffinity labeled with 8-N-3[P-32]cAMP. The whole lysates and cytop lasmic fraction exhibited the presence of both RI alpha and RII alpha - subunits of PKA. The fractions exhibiting high activity of the marke r enzymes for plasma membranes, Golgi apparatus and mitochondria conta ined mainly RII alpha. In the fractions of lysosomes and microsomes RI alpha and RII alpha were found in nearly equal amounts.