Promoters for RNA polymerase III may consist of bipartite sequences downstream of the startpoint, with boxA separated from either boxC or boxB. Or they may consist of separated sequences upstream of the startpoint (Oct, PSE, TATA). 5S rRNA genes have type 1 promoters, tRNA genes have type 2 promoters, and some U snRNA genes have upstream type promoters (note: most, but not all, U snRNA genes are transcribed by RNA polymerase II) .