Synthesis and phosphorylation of an extracellular polypeptide reacting with anti-MYC antisera in primary rat hepatocyte cultures.
Primary hepatocytes stimulated with appropriate growth factors enter into S phase and it is believed that c-myc and other cell cycle-related genes play an important role in the G0-G1/S phase transition. Four polypeptides reacting with anti-MYC antisera were detected in normal primary rat hepatocyte lysates, showing a pattern of 55-67 KDa on SDS-PAGE. A 67 KDa polypeptide was detected in the extracellular medium of the hepatocyte culture capable of undergoing phosphorylation. Both extracellular and intracellular polypeptides reacting with MYC-specific antisera exhibited an unusually long half life. It is believed that the intracellular MYC polypeptides may represent degradation products or species undergoing at present unknown post-transcriptional modification(s). We suggest that the extracellular MYC polypeptide(s) may be involved in the regulation of cell growth and differentiation.
Skouteris
G G
GG
Department of Pathology, Duke University Medical Center, Durham, North Carolina.
Michalopoulos
G K
GK
D000818:Animals; D001345:Autoradiography; D002104:Cadmium / Q000494:pharmacology; D019256:Cadmium Chloride; D002478:Cells, Cultured; D004591:Electrophoresis, Polyacrylamide Gel; D005110:Extracellular Space / Q000378:metabolism; D007106:Immune Sera; D007700:Kinetics; D008099:Liver / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D008715:Methionine / Q000378:metabolism; D008970:Molecular Weight; D010710:Phosphates / Q000378:metabolism; D010761:Phosphorus Radioisotopes; D010766:Phosphorylation; D016271:Proto-Oncogene Proteins c-myc / Q000096:biosynthesis / Q000276:immunology / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D013462:Sulfur Radioisotopes
D007106:Immune Sera; D010710:Phosphates; D010761:Phosphorus Radioisotopes; D016271:Proto-Oncogene Proteins c-myc; D013462:Sulfur Radioisotopes; D002104:Cadmium; D008715:Methionine; D019256:Cadmium Chloride