Amino Acid Sequence Analysis of Reverse Transcriptase Subunits from Avian Myeloblastosis Virus

Abstract
The NH2-terminal amino acid sequences of the .alpha. and .beta. chains of avian myeloblastosis .alpha..beta. DNA polymerase were determined by using microsequence analysis in the subnanomole range and were identical up to 17 residues. The common sequence was as follows: Thr-Val-Ala-Leu-His-Leu-Ala-Ile-Pro-Leu-Lys-Trp-Lys-Pro-Asn-His-Thr-. This result provides convincing chemical evidence that the .alpha. chain is derived from the NH2-terminal region of the .beta. chain by proteolytic cleavage, whereas the amino acid composition for these .alpha. and .beta. subunits and [polypeptide] p32 DNA endonuclease suggests that the latter is derived from the carboxyl-terminal region of the .beta. chain.