Frequent alternative splicing of human genes

Alternative splicing can produce variant proteins and expression patterns a s different as the products of different genes, yet the prevalence of alter native splicing has not been quantified. Here the spliced alignment algorit hm was used to make a first inventory of exon-intron structures of known hu man genes using EST contigs from the TIGR Human Gene Index. The results on any one gene may be incomplete and will require verification, yet the overa ll trends are significant. Evidence of alternative splicing was shown in 35 % of genes and the majority of splicing events occurred in 5' untranslated regions, suggesting wide occurrence of alternative regulation. Most of the alternative splices of coding regions generated additional protein domains rather than alternating domains.