TABLE 1.

Comparison of amino acids in the env gene products of PVC-441 MuLV, PVC-211 MuLV, and F-MuLV^a

Positionb		Amino acid (charge) in:			Structural elementc
env	SU	PVC-441	PVC-211	F-MuLV
7		Ser	Ser	Pro
74	40	Asp (−1)	Asp (−1)	Val
95	61	Arg (+1)	Arg (+1)	Gln	I
113	79	Asn	Asn	Ser	I
114	80	Arg (+1)	Arg (+1)	Ser	I
118	84	Ala	Ala	Ser	I
150	116	Gly	Gly	Glu (−1)	Hinge
163	129	Glu (−1)	Lys (+1)	Glu (−1)	II
186	152	Ala	Ala	Val	II
206	172	Asn	Asn	Ser
209	175	Ala	Ala	Val
237	203	Ile	Ile	Thr
250	216	Gln	Gln	Arg (+1)
261	227	Lys (+1)	Lys (+1)	Arg (+1)
283	249	Phe	Phe	Leu
285	251	Leu	Leu	Arg (+1)
297	263	Ser	Ser	Pro
311	277	Ala	Ala	Thr
353	319	Ala	Ala	Gly
378	344	Ala	Ala	Val
379	345	Gly	Gly	Ala
392	358	Gln	Gln	Arg (+1)
413	379	Thr	Thr	Ile
414	380	Gly	Gly	Asp (−1)
424	390	Ala	Ala	Thr
427	393	Met	Met	Thr
676		Gln	Gln	TERd

^aAmino acid sequences of the env product of PVC-441, PVC-211, and F-MuLV were deduced from the nucleotide sequences and compared. 

^bThe amino-terminal methionine of the envelope precursor protein is numbered 1 (env), and the amino-terminal alanine of the SU protein is numbered 1 (SU). 

^cStructural elements are described by Linder et al. (5). 

^dTER, termination codon.