GENOMIC ORGANIZATION OF THE HUMAN VP16 ACCESSORY PROTEIN, A HOUSEKEEPING GENE (HCFC1) MAPPING TO XQ28

The region between DXS52 and Factor VIII gene in the human Xq28 chromo somal band contains a G + C-rich isochore to which many genes have bee n mapped. We report here the isolation and characterization of a trans cript mapping about 50 kb telomeric from the vasopressin type 2 recept or gene in a 180-kb YACs/cosmid contig containing the L1CAM gene at it s centromeric end. The determined transcribed sequence from a human fe tal brain library is identical to that of the recently identified acce ssory protein HCFC1 (host cell factor, also called C1) that activates herpes simplex virus VP16 (alpha TIF) transactivator protein for assoc iation with the octamer motif-binding protein Oct-1 (Cell 74: 115, 199 3). The gene is expressed in a ubiquitous pattern and a larger transcr ipt of approximately 10 kb is present in all the tissues tested, while an alternatively spliced RNA of approximately 8.0 kb is present in mu scle and heart tissues. Genomic sequencing allowed us to determine tha t the sequenced transcript is assembled from 26 exons spread over a re latively small genomic region of approximately 24 kb. This allowed us to determine that a previously reported cDNA clone arises from the spl icing out of an internal portion of exon 8 which does not change the r eading frame. Ah together these results raise the possibility that alt ernative mRNA processing could partly contribute to the diversity of t he polypeptide HCFC1 family in a subset of tissues. (C) 1994 Academic Press, Inc.