N-terminal amino acid sequences of the polyoma middle-size T antigen are important for protein kinase activity and cell transformation.

AUTOR(ES)

Templeton, D

RESUMO

We constructed deletion mutations which removed N-terminal coding sequences of various lengths from a cloned polyoma middle-size T antigen (MT antigen) gene. We introduced the MT antigen genes into a simian virus 40 expression vector so that they were expressed at high levels under the control of the simian virus 40 late promoter in COS-1 cells. The deletion mutant genes synthesized truncated MT antigens whose size was consistent with the deletion of either 70 or 106 amino acids from N termini, owing to initiation of translation at internal methionine codons in the MT antigen-coding region. The truncated MT antigens were found in cell membrane fractions but failed to show MT antigen-associated protein kinase activity. The cloned deletion mutant DNAs failed to transform rat F2408 or mouse NIH 3T3 cells. Therefore, N-terminal amino acid sequences of the polyoma MT antigen, as well as C-terminal sequences, are important for protein kinase activity and cell transformation.

Documentos Relacionados

• Antibodies specific for the polyoma virus middle-size tumor antigen.
• Deletion mapping of a short polyoma virus middle T antigen segment important for transformation.
• Polyoma viral middle T-antigen is required for transformation.
• Biosynthesis, glycosylation, and partial N-terminal amino acid sequence of the T-cell-activating protein TAP.
• N-terminal amino acid sequences and amino acid compositions of the Spirochaeta aurantia flagellar filament polypeptides.