Identification of ZFR, an ancient and highly conserved murine chromosome-associated zinc finger protein

In a screen for RNA binding proteins expressed during murine spermatogenesis, we cloned a novel, ancient zinc finger protein possessing a region common to a small class of RNA binding proteins. Zfr (zinc finger RNA binding) encodes a protein of 1052 amino acids with three widely spaced Cys2His2 zinc fingers. Outside of the zinc fingers, ZFR shares a region that is highly conserved between several RNA binding proteins containing copies of the double-stranded RNA binding motif. By northern blotting, Zfr is expressed at highest levels within the testis, ovary and brain. Immunohistochemistry and confocal microscopy were used to show that ZFR is highly expressed during meiosis I in males and females and is chromosome associated. Zfr is also expressed in Sertoli cells in the testis and granulosa cells in the ovary where it is localized to the nucleus. Using fluorescent in situ hybridization we mapped Zfr to chromosome 15 region A. ZFR appears to be an ancient protein, as apparent homologs exist in invertebrates (D. melanogaster) nematodes (C. elegans) and humans (H. sapiens).     

Cloning and characterization of a novel human gene encoding a zinc finger protein with 25 fingers

This study reports cloning and characterization of a human cDNA encoding a novel human zinc finger protein, ZFD25. ZFD25 cDNA is 6118 bp long and has an open reading frame of 2352 bp that encodes a 783 amino acid protein with 25 C2H2-type zinc fingers. The ZFD25 cDNA also contains a region with high sequence similarity to the Krüppel-associated box A and B domain in the 5'-untranslated region, suggesting that ZFD25 belongs to the Krüppel-associated box zinc finger protein family. The ZFD25 gene was localized to chromosome 7q11.2. Northern blot analysis showed that ZFD25 was expressed in a wide range of human organs. In cultured endothelial cells, the mRNA level was decreased upon serum starvation.     

Multiple genes encoding zinc finger domains are expressed in human T cells

Proteins containing zinc finger domains have been implicated in developmental control of gene expression in Drosophila, Xenopus, mouse, and humans. Multiple cDNAs encoding zinc (II) finger structures were isolated from human cell lines of T-cell origin to explore whether zinc finger genes participate in the differentiation of human hematopoietic cells. Initial restriction analysis, genomic Southern blotting, and partial sequence comparisons revealed at least 30 nonoverlapping cDNAs designated cKox(1-30) encoding zinc finger motifs. Analysis of cKox1 demonstrated that Kox1 is a single-copy gene that is expressed in a variety of hematopoietic and nonhaematopoietic cell lines. cKox1 encodes 11 zinc fingers that were shown to bind zinc when expressed as a beta-gal-Kox1 fusion protein. Further analysis of the predicted amino acid sequence revealed a heptad repeat of leucines NH2-terminal to the finger region, which suggests a potential domain for homo- or heterodimer protein formation. On the basis of screening results it was estimated that approximately 70 zinc finger genes are expressed in human T cells. Zinc finger motifs are probably present in a large family of proteins with quite diverse and distinct functions. However, comparisons of individual finger regions in cKox1 with finger regions of cKox2 to cKox30 showed that some zinc fingers are highly conserved in their putative alpha-helical DNA binding region, supporting the notion of a zinc finger-specific DNA recognition code.