Acts as a transcriptional activator or repressor. Positively regulates the expression of alpha A crystallin genes during lens fiber cell differentiation. Binds to Maf recognition elements (MARE). Homodimer or heterodimer. Binds DNA as a homodimer or a heterodimer. Interacts with HOXD12, PAX6 and PRRX1; interaction is direct and inhibits its DNA-binding and transactivating activity. Expressed in kidney, brain, lung, gut, mesenterium, testis and ovary. Expressed in the lens placode at stage 14. Expressed at stage 18 when the invaginating lens placode closes to form the lens vesicle. The basic region and the leucine zipper structure are necessary for association with HOXD12 and PRRX1. Belongs to the bZIP family. Maf subfamily.