The amino acid sequences of the putative polypeptides of maize streak virus (MSV) have been systematically compared with those of cassava latent virus (CLV) and tomato golden mosaic virus (TGMV) using the programme D I A G O N (8).
Conserved sequences have been detected between peptides encoded by the complementary ( -) sense of MSV and those of CLV and TGMV, viz; the 40 200 M r polypeptide of CLV-1 (3) and the 40 285 M r polypeptide of TGMV-A (4) show extensive homologies with the 17 768 M r and 31 388 M r polypeptides of MSV (6).
Distant and variable homologies have been detected between the putative coat protein of MSV when compared with those of CLV and TGMV. No other relationships between the potential gene products of MSV and those of CLV and TGMV have been detected.
The extensive homologies detected between the complementary sense encoded peptides suggest that they are derived from functional genes, and that the directly conserved sequences may contain amino acids essential to the function of these proteins. The less extensive homologies among the putative coat proteins are considered in relation to their possible structures and functions.