Vertebrate LTR retrotransposons of the Tf1/Sushi group

LTR retrotransposons of the Tf1/sushi group from a diversity of vertebrates , including fish, amphibians, and mammals (humans, mice, and others), are d escribed as full-length or partial elements. These elements are compared, a nd the mechanisms involved in self-priming of reverse transcriptase and pro grammed phase shifting are inferred. Evidence is presented that in mammals these elements are still transcriptionally active and are represented as pr oteins. This suggests that members of the Tf1/sushi group are present as fu nctional elements (or incorporated as partial elements into host genes)in d iverse vertebrate lineages.