Characterization and purification of a protein kinase C substrate in human B cells. Identification as lymphocyte-specific protein 1 (LSP1).
Incubation of B-chronic lymphocytic leukemia (B-CLL) cells with phorbol esters resulted in the phosphorylation of two major PKC substrates, MARCKS (myristoylated, alanine-rich C kinase substrate) and MRP (MARCKS-related protein), and of a third protein, with an apparent m.w. of 60,000 that was the most prominent protein kinase C substrate in these cells. p60 phosphorylation was time and PMA dose dependent, and was induced by cell-permeable diacylglycerol, but not by inactive phorbol esters. Two-dimensional electrophoretic analysis of the protein phosphorylation pattern from the B cell line CESS demonstrated the identity between the p60 protein expressed in this cell line and that expressed in B-CLL cells. p60 was purified from CESS cells and peptide microsequencing of this protein revealed that it was lymphocyte-specific protein 1 (LSP1), that is here characterized as the most prominent protein kinase C substrate in B cells.
Carballo
E
E
Biological Hematology Service, University of Barcelona, Spain.
Colomer
D
D
Vives-Corrons
J L
JL
Blackshear
P J
PJ
Gil
J
J
D000199:Actins / Q000378:metabolism; D000595:Amino Acid Sequence; D001402:B-Lymphocytes / Q000201:enzymology* / Q000276:immunology; D002135:Calcium-Binding Proteins / Q000032:analysis*; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D015451:Leukemia, Lymphocytic, Chronic, B-Cell; D008565:Membrane Proteins; D008840:Microfilament Proteins; D008969:Molecular Sequence Data; D000076250:Myristoylated Alanine-Rich C Kinase Substrate; D010750:Phosphoproteins / Q000737:chemistry* / Q000302:isolation & purification; D010766:Phosphorylation; D011493:Protein Kinase C / Q000737:chemistry* / Q000302:isolation & purification; D011506:Proteins / Q000032:analysis; D011518:Proto-Oncogene Proteins / Q000032:analysis; D016760:Proto-Oncogene Proteins c-fos / Q000032:analysis; D051076:Proto-Oncogene Proteins c-fyn; D013379:Substrate Specificity; D014407:Tumor Cells, Cultured
D000199:Actins; D002135:Calcium-Binding Proteins; D047908:Intracellular Signaling Peptides and Proteins; C489183:LSP1 protein, human; C000619710:MARCKS protein, human; D008565:Membrane Proteins; D008840:Microfilament Proteins; D010750:Phosphoproteins; D011506:Proteins; D011518:Proto-Oncogene Proteins; D016760:Proto-Oncogene Proteins c-fos; D000076250:Myristoylated Alanine-Rich C Kinase Substrate; C494957:FYN protein, human; D051076:Proto-Oncogene Proteins c-fyn; D011493:Protein Kinase C