Diagram of CaLCuV AC2 and SCTV C2 proteins used in over-expression studies. (A) The linear drawing represents functional domains (span of amino acids indicated) present within the full-length CaLCuV AC2 protein. The N-terminal region contains a basic region of four arginine residues and a potential nuclear localization sequence. The C-terminus contains a minimal transcription activation domain within an acidic region. A region containing conserved cysteine and histidine residues forms a putative zinc finger domain, with a high degree of homology with the SCTV C2 protein. (B) Truncated form of the CaLCuV AC2 protein lacking the C-terminal 29 amino acids containing the acidic activation domain. (C) Full-length SCTV C2 protein, which lacks an acidic activation domain, but has homology to the putative zinc finger domain in CaLCuV AC2.