A human protein (RUVBL1), consisting of 456 amino acids (50 kDa) and h
ighly homologous to RuvB, was identified by using the 14-kDa subunit o
f replication protein A (hsRPA3) as bait in a yeast two-hybrid system.
RuvB is a bacterial protein involved in genetic recombination that be
ars structural similarity to subunits of the RF-C clamp loader family
of proteins. Fluorescence in situ hybridization analysis demonstrated
that the RUVBL1 gene is located at 3q21, a region with frequent rearra
ngements in different types of leukemia and solid tumors. RUVBL1 co-im
munoprecipitated with at least three other unidentified cellular prote
ins and was detected in the RNA polymerase II holoenzyme complex purif
ied over multiple chromatographic steps. In addition, two yeast homolo
gs, scRUVBL1 and scRUVBL2 with 70 and 42% identity to RUVBL1, respecti
vely, were revealed by screening the complete Saccharomyces cerevisiae
genome sequence. Yeast with a null mutation in scRUVBL1 was nonviable
. Thus RUVBL1 is an eukaryotic member of the RuvB/clamp loader family
of structurally related proteins from bacteria and eukaryotes that is
essential for viability of yeast.