Sequence of a putative human housekeeping gene (HK33) localized on chromosome 1

A gene (HK33) localized on human chromosome 1 has been detected by crossreaction of its fusion protein with a monospecific antiserum directed against human vitamin-D-binding protein (hDBP; group-specific component). Its cDNA sequence analysis showed no evident homologies neither to the sequence encoding hDBP nor to any other sequence. The largest cDNA clone of 3.2 kb includes a 897-bp coding region and a large 3' untranslated region with at least four polyadenylation sites. Further cDNA amplification using PCR demonstrated a total cDNA length of approx. 3.7 kb. Northern blot analysis revealed signals at about 2.2-2.5 kb and 4.0 kb, the shorter transcripts representing mRNAs using one of the two polyadenylation sites at about 2.0 kb. Synthesis of the 299-amino-acid polypeptide (33 kDa) in the bacterial host, with subsequent Western blot analysis, verified the sequence-specific recognition by the hDBP-specific antiserum. The search of protein databanks revealed no homology of HK33 to any known sequence. Since the gene is transcribed in all cells and tissues tested so far, it is a strong candidate for another housekeeping gene.