GENOMIC STRUCTURE AND ASSIGNMENT OF THE RHOH TTF SMALL GTPASE GENE (ARHH) TO 4P13 BY IN-SITU HYBRIDIZATION/

The RhoH/TTF (ARHH) gene encodes a new member of the Ras superfamily o f small GTPases. The gene was identified by fusion to the BCL6/LAZ3 on cogene in an initially described t(3;4)(q27;pll) translocation in a no n-Hodgkin's lymphoma cell line. The predicted amino acid sequence of t he RhoH/TTF gene product includes Rho-like GTPase structural motifs. T he RhoH/TTF gene is restrictively expressed in hematopoietic cells and tissues. Mutations in the human RAS genes have been shown previously to be tumorigenic; in the search for a potential implication of the Rh oH/TTF gene in hemopoietic malignancies, we established its genomic st ructure. The RhoH/TTF gene spans 35 kb and contains two exons, with th e second bearing the entire amino-acid-coding region. Chromosomal mapp ing, by FISH experiments, places the RhoH/TTF gene on the short arm of chromosome 4, band p13. (C) 1997 Academic Press.