title: Identification of a precursor protein to the major glycoproteins of mouse mammary tumor virus.
abstract: Mouse mammary tumor virus-producing cultures of mouse mammary tumor cells synthesize a viral-related polypeptide of molecular weight of 73,000 (gp 73) which is rapidly labeled during a short pulse but disappears during the chase concomitantly with the appearance of label in the virion glycoproteins gp 49 and gp 37.5/33.5. The addition of the protein synthesis-inhibitor cycloheximide to the chase medium has little effect on this conversion. Treatment of the proposed precursor with alpha-chymotrypsin leads to the formation of a polypeptide of molecular weight 49,000, similar to the major virion glycoprotein. A comparison of tryptic digest maps of the glycoproteins involved supports the hypothesis that both the viral glycoproteins gp 49 and gp 37.5/33.5 are derived from gp 73.
mesh_terms: D000818:Animals; D002918:Chymotrypsin / Q000378:metabolism; D046508:Culture Techniques; D003513:Cycloheximide / Q000494:pharmacology; D006023:Glycoproteins / Q000032:analysis*; D008325:Mammary Neoplasms, Experimental; D008324:Mammary Tumor Virus, Mouse / Q000032:analysis* / Q000378:metabolism; D008970:Molecular Weight; D010455:Peptides / Q000032:analysis; D011498:Protein Precursors / Q000032:analysis* / Q000378:metabolism; D014357:Trypsin / Q000378:metabolism; D014764:Viral Proteins / Q000032:analysis* / Q000096:biosynthesis / Q000378:metabolism
chemical_list: D006023:Glycoproteins; D010455:Peptides; D011498:Protein Precursors; D014764:Viral Proteins; D003513:Cycloheximide; D002918:Chymotrypsin; D014357:Trypsin