Pathogenicity determinant (By similarity). May act as a suppressor of RNA-mediated gene silencing, also known as post-transcriptional gene silencing (PTGS), a mechanism of plant viral defense that limits the accumulation of viral RNAs. May repress the AL61 promoter. Interacts with Arabidopsis thaliana ASK7/ASK-eta and ASK6/ASK-zeta proteins. Localizes to the cell periphery. Phosphorylated by Arabidopsis thaliana ASK7/ASK-eta mainly on threonine and serine residues. Belongs to the geminiviridae protein AC4/C4 family.