Structure of the pX protein deduced from the nucleotide sequence of a cDNA clone of pX mRNA in cells infected with human T-cell leukemia virus type I.

A splice donor site of pX mRNA of human T-cell leukemia virus type I was elucidated by analyzing a cDNA clone of poly A+ RNA isolated from cat fibroblast cells infected with the virus. The donor site was located near the 5' end of the env gene. The putative N-terminal amino acid sequence of the pX protein was deduced to be Met-Ala-His---.