InterPro domain: IPR022776

This zinc binding domain [ 1 ] has four conserved zinc chelating residues in a CHHC pattern and is known as the CHHC U11-48K-type zinc finger.

The CHHC U11-48K-type zinc finger is found only in eukaryotes. It has been identified in spliceosomal U11-48K proteins, tRNA methyl-transferases TRM13 and gametocyte specific factors (GTSF). The CHHC U11-48K-type zinc finger (~30 residues) is present in a single copy in U11-48k AND TRM13, whereas GTSF contains two repeats separated by a short linker. The CHHC U11-48K-type zinc finger may function as a RNA recognition and binding module [ 2 , 2 ].

The CHHC U11-48K-type zinc finger contains four invariant Cys and His residues with a consensus sequence of C-x(5,7)-H-x(7,9)-H-x(3,4)-C. It stochiometrically binds zinc ions in a one-to-one ratio. The structure of the CHHC U11-48K-type zinc finger consists of a beta hairpin followed by a helix. the zinc ion is coordinated by Cys and His residues from the beta hairpin and by His and Cys residues from the helix, respectively. The helical region has an alpha-helical conformation that is interrupted in the middle by a single pi-helical turn [ 3 ].

1. A novel CHHC Zn-finger domain found in spliceosomal proteins and tRNA modifying enzymes. Bioinformatics 24, 2277-80
2. Solution structure of the U11-48K CHHC zinc-finger domain that specifically binds the 5' splice site of U12-type introns. Structure 17, 294-302