May contribute to developmentally specific patterns of gene expression. Binds specifically to ocs elements which are transcriptional enhancer found in the promoters of several plant genes. OCSBF-1 is able to bind to a site within each half of the ocs element as well as to animal AP-1 and CREB sites. Roots and shoots of young plants, and basal portion of leaves. A derivative of OCSBF-1 that contains only the 76 N-terminal amino acids is still able to bind to the ocs element. Belongs to the bZIP family.