. "U.S.A. 90:6320; Patel et al., 1995, Biochemistry 34:5351) occur in the context hxDD(F/Y) in the telomerase RTs compared to (F/Y)xDDh in the other RTs (where h is a hydrophobic amino acid, and ???x??? is any amino acid; see Xiong et al., 1990, EMBO J. 9:3353; Eickbush, in The Evolutionary Biology of Viruses, (S. Morse, Ed., Raven Press, N.Y., p. 121, 1994))." . . .