Complex RNA processing of TDRKH, a novel gene encoding the putative RNA-binding Tudor and KH domains

The sequence from a human EST (IMAGE:259322) with homology to the nucleotid e-sensitive chloride conductance regulator (ICln) was used to screen a huma n aortic cDNA library. The probe sequence was from a region of the EST lack ing homology to ICln, and the goal was to isolate an ICln-like gene. A 2843 bp cDNA clone with an open reading frame coding for a 561 amino acid prote in was isolated. This clone had no homology to ICln. PROSITE analysis of th e putative protein sequence reveals one tudor and two K homology (KH) domai ns. The gene has therefore been named TDRKH. Both KH and tudor motifs are i nvolved in binding to RNA or single-strand DNA. PCR analysis demonstrated t hat TDRKH is alternatively spliced in several ways and alternatively polyad enylated at multiple sites. Northern analysis confirmed the presence of mes sages of multiple lengths with predominant bands at 2.8 and 4.0 kb and also demonstrated that TDRKH is widely expressed in human tissues. Within an in tron of TDRKH, there is a legion with 90% homology to ICln. This sequence, which is incorporated into the alternatively spliced message represented by IMAGE:259322, contains a 2 bp deletion that disrupts the ICln reading fram e and therefore represents an ICln pseudogene. The TDRKH gene was mapped to the Epidermal Differentiation Complex (EDC) at chromosome lq21 by radiatio n hybrid mapping and STS content of genomic clones from that region. The ED C contains a large cluster of related genes involved in terminal differenti ation of the epidermis. It remains to be determined whether TDRKH has a spe cific role in epithelial function. (C) 2000 Elsevier Science B.V. All right s reserved.