Maturation of mouse mammary tumor virus envelope protein is blocked by a specific point mutation.
Expression of a mouse mammary tumor virus (MMTV) envelope gene, ENV2, in COS-7 cells resulted in the synthesis of a precursor protein Pr74 that underwent complete proteolytic processing to the mature envelope species gp52 and gp33. In contrast, expression of a second MMTV envelope gene, ENV1, in COS-7 cells resulted in the synthesis of a precursor protein Pr74 that failed to undergo proteolytic processing to the mature products. Expression and sequencing of various chimeric ENV1/ENV2 genes determined that a single glycine-to-glutamic acid mutation at position 54 was responsible for the nonprocessable phenotype of ENV1-encoded Pr74. The significance of this point mutation in relation to the requirements for precursor protein folding and maturation are discussed.
Bedgood
R M
RM
Department of Pathology, University of Southern California Health Sciences Center, Los Angeles 90033.
Snider
L D
LD
Stallcup
M R
MR
D000818:Animals; D002478:Cells, Cultured; D015752:Genes, env / Q000235:genetics*; D008324:Mammary Tumor Virus, Mouse / Q000378:metabolism*; D009154:Mutation / Q000235:genetics; D011498:Protein Precursors / Q000378:metabolism*; D011499:Protein Processing, Post-Translational; D014759:Viral Envelope Proteins / Q000378:metabolism*
D011498:Protein Precursors; D014759:Viral Envelope Proteins