A comprehensive catalog of human KRAB-associated zinc finger genes: insights into the evolutionary history of a large family of transcriptional repressors
Key findings
Huntley et al. employed profile Hidden Markov Model software to scan the human genome for KRAB, SCAN, and Krüppel-type finger motifs, followed by manual curation of gene models. The analysis identified 423 KRAB-ZNF protein-coding loci generating 818 different transcripts that encode 742 structurally distinct proteins through alternative splicing. The catalog also documented 341 pseudogene sequences including 227 gene fragments, 39 full-length pseudogenes, and 75 processed pseudogenes.
Comparative genomics across human, chimpanzee, dog, and mouse genomes revealed 103 KRAB-ZNF genes conserved in mammals alongside substantial lineage-specific diversification, with at least 136 genes being primate-specific including many recent duplicates. Clustering analysis showed 384 genes organized into 65 gene clusters with the largest concentrations on chromosome 19, demonstrating evolution primarily through tandem in situ duplication and segmental duplication events.
The researchers created a publicly accessible Web-based resource at http://znf.llnl.gov/ providing curated gene models, full sequences, and motif descriptions for all 423 KRAB-ZNF loci. The platform integrated with the UCSC Genome Browser, offered searchable interfaces, and included downloadable HMMER matrices and structural data files to facilitate genome-wide analysis of this transcriptional repressor family.