Members of the MAZ Family: A Novel cDNA Clone for MAZ from Human Pancreatic Islet Cells

Abstract

A human recombinant cDNA clone that encoded a zinc-finger protein (Myc-associatedzinc-finger protein of humanislet; MAZi) was cloned by screening a cDNA library prepared from human pancreatic islet cells. The encoded protein showed a high degree of homology to theMyc-associated zinc-finger protein MAZ (ZF87 or Pur-1). However, differences between the cDNAs for MAZi and MAZ were found in the length of the encoded polyalanine stretch and in the sequence of the 5′-end leader. MAZi transcripts were significantly more abundant in rat pancreatic islet carcinoma tissue than in normal rat islet cells. Moreover, MAZi protein bound specifically to the pyrimidine-rich strand of the CT-element of thec-mycgenein vitroand strongly induced the expression of chloramphenicol acetyltransferase (CAT) from ac-mycpromoter/CAT reporter construct in human pancreatic cells. Our results suggest that a distinct member of the MAZ family is expressed in human islet cells and enhances the transcriptional activity of thec-mycgene.