Gene structure and expression of phospholemman in mouse

Phospholemman (PLM) is a small transmembrane cardiac protein that is the ma jor sarcolemmal substrate for phosphorylation in response to adrenergic sti mulation. PLM likely plays a role in muscle contractility and cell volume r egulation through its function as a channel or a channel regulator. We are the first to describe the structure of the PLM gene and to demonstrate PLM cDNA splice variants. We cloned the murine PLM cDNA and used it as a probe to isolate the gene from a 129/SvJ genomic library. The gene contains seven introns and eight exons. The coding sequence is interrupted by five intron s; the 5 ' untranslated region by two. Using rapid amplification of 5 ' cDN A ends we identified transcription start sites and four splice variants of the 5 ' untranslated domain. There was no TATA box or CAAT box in the putat ive promoter regions. The gene has several stretches of dinucleotide repeat s. The 3 ' untranslated domains of mouse PLM cDNA clones show sequence diff erences not accounted for by alternative splicing. Mouse PLM shares 93, 83 and 80% amino acid identity with rat, dog, and human PLMs, respectively. Ti ssue expression of murine PLM parallels that in other species, being highes t in heart, skeletal muscle, and liver. (C) 2001 Elsevier Science B.V. All rights reserved.