The AL1 proteins encodes the replication initiator protein (Rep) of geminiviruses, which is a replicon-specific initiator enzyme and is an essential component of the replisome [1]. For geminivirus Rep protein, this N-terminal region is crucial for origin recognition and DNA cleavage and nucleotidyl transfer [1].

1: The structure of a replication initiator unites diverse aspects of nucleic acid metabolism. Campos-Olivas R, Louis JM, Clerot D, Gronenborn B, Gronenborn AM; Proc Natl Acad Sci U S A 2002;99:10310-10315. PMID:12130667