Genomic organization of the human retinoblastoma gene

Sequence analysis of the human retinoblastoma gene cDNA revealed the presence of repeated elements in the form of direct repeats, inverted repeats and dyad symmetries. The clustering of the dyad symmetrical elements in some exons, #16 and #17, coincides with the hot spots for structural aberrations of the RB-1 locus previously observed in tumors. The RB-1 gene is divided into at least 27 exons distributed over 200 kbp. Three potential Sp1 binding sites are presented within 600 bp upstream of the translation start site. A DNA fragment containing these Sp1 sites ligated to a promotorless CAT gene can promote its transcription in transfected cell culture.