Isolation, characterization, and mapping of a novel human KRAB zinc finger protein encoding gene ZNF463

A novel human KRAB (Krüppel associated box) type zinc finger protein encoding gene, ZNF463, was obtained by mRNA differential display and RACE. It consists of 1904 nucleotides and encodes a protein of 463 amino acids with an amino-terminal KRAB domain and 12 carboxy-terminal C2H2 zinc finger units. The gene is mapped to chromosome 19q13.3 approximately 4 by FISH. As from Northern blot analysis ZNF463 is only expressed in testis, RT-PCR indicates that ZNF463 is expressed more highly in normal fertile adults than in fetus and azoospermic patients suggesting that it may play a role in human spermatogenesis.     

Nuclear transport and phosphorylation of the RNA binding Xenopus zinc finger protein XFG 5-1.

XFG 5-1 is a Krüppel-type Xenopus zinc finger protein with specific RNA homopolymer binding activity in vitro. In the oocyte, the protein is distributed between nucleus and cytoplasm; the nuclear fraction, not the cytoplasm, contains phosphorylated isoform(s) of XFG 5-1. In vitro phosphorylation by use of oocyte/egg extracts or purified casein kinase II is specific to the amino-terminal portion of the protein. The carboxy-terminal zinc finger domain contains a signal sufficient for nuclear transport. Overexpression of either full length XFG 5-1 or of the carboxy-terminal portion alone, which maintains RNA binding and nuclear import activities, was achieved in Xenopus embryos by mRNA injection. This treatment did not result in impaired regulation of development, suggesting that XFG 5-1 functions in a way distinct from the mode of action exemplified in the Drosophila zinc finger protein Krüppel.     

A novel zinc finger protein,ZZaPK, interacts with ZAK and stimulates the ZAK-expressing cells re-entering the cell cycle

ZAK has been implicated in cell cycle arrest regulation through its function on decreasing cyclin E expression. To explore the mechanistic basis for this regulation, the yeast two-hybrid system was used with a novel Krüppel-type C2H2 zinc finger member cloned. This cloned cDNA encodes a novel protein with Krüppel-type zinc fingers designed as ZZaPK (zinc finger and ZAK associated protein with KRAB domain) and is widely expressed. ZZaPK, when it is expressed in cells, is growth promoted and might lead to increasing E2F expression and induce cyclin E/CDK2 activity, which counteracts the ZAK function. The model proposed here is that ZAK might play a role as an upstream signal to suppress the ZZaPK function and decrease E2F expression.     

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.