Tissue-Specific Alternative Promoters Regulate the Expression of the Two Sarco/Endoplasmic Reticulum Ca-ATPase Isoforms fromArtemia franciscana

摘要

ABSTRACTThe sarco/endoplasmic reticulum Ca-ATPase gene fromArtemia franciscanais transcribed into two mRNAs of 4.5 and 5.2 kb that code for protein isoforms differing at their carboxyl terminus. Northern blot assays and anchored polymerase chain reaction (PCR) experiments have shown that these two mRNAs also differ at the initial part of their 5′ untranslated region. The 5.2-kb mRNA-specific 5′ untranslated region is present as an independent exon whose transcription is regulated by a promoter different from the one previously described that regulates the expression of the 4.5-kb mRNA. The nucleotide sequence of the 5.2-kb mRNA promoter and the transcription initiation site have been determined. These results suggest that the expression of the two protein isoforms is regulated inA. franciscanaat the transcription initiation step, in contrast with the vertebrates sarco/endoplasmic reticulum Ca-ATPase genes 1 and 2 which have unique promoters for transcription of the two isoforms encoded by each g