Evidence for alternate splicing within the mRNA transcript encoding the DNA damage response kinase ATR

Proper cellular response to genotoxic insult often requires the activity of one or more members of a family of high-molecular weight protein kinases r eferred to as phosphatidylinositol-3 kinase (PIK)-like proteins. While cata lytic activity is an indispensable part of PIK-like protein function, littl e is currently known about factors that control their activity and/or funct ions. This deficiency stems, in large part, from our lack of knowledge conc erning functionally significant subdomains within the large non-catalytic d omain of these proteins. We have determined that the transcript encoding th e PIK-like protein ATR undergoes alternate splicing within the region of th e mRNA encoding its non-catalytic domain. This conclusion is based on the s equencing of a human expressed sequence tag clone encoding a portion of the ATR cDNA, and is supported by the results of reverse transcriptase-polymer ase chain reaction (RT-PCR) assays conducted on total and polyA + RNA, as w ell as sequencing of cloned RT-PCR products. Cloning and sequencing of a se gment of human genomic DNA indicated that this event arises from splicing o f a single 192 bp exon within the ATR gene. Analysis of several human tissu es indicated that alternate ATR transcripts are differentially expressed, s uggesting that this region of the ATR protein may be of functional importan ce. (C) 2001 Published by Elsevier Science B.V. All rights reserved.