title: Evidence for two isoforms of the endoplasmic-reticulum Ca2+ pump in pig smooth muscle.
abstract: cDNA clones coding for the endoplasmic reticulum Ca2+-transport ATPase have been cloned from a pig smooth-muscle cDNA library. The transcripts can be divided into two classes which differ in their 3' ends due to alternative splicing of the primary gene transcript. The class 1 cDNA encodes a protein of 997 amino acids (Mr 110,000). The class 2 protein (1042 amino acids; Mr 115,000) is completely identical to the class 1 protein except that the four C-terminal amino acids of the class 1 protein are replaced in the class 2 protein with a tail of 49 amino acids. Comparison of these sequences with other Ca2+ pump sequences reveals that the class 1 isoform corresponds to the sarcoplasmic reticulum Ca2+ pump of slow-twitch skeletal/cardiac muscle, whereas the class 2 protein corresponds to a Ca2+ pump recently detected in non-muscle tissues.
authors.affiliation: Laboratorium voor Fysiologie, Leuven, Belgium.
authors.forename: J A
authors.initials: JA
authors.lastname: Eggermont
authors.forename: F
authors.initials: F
authors.lastname: Wuytack
authors.forename: S
authors.initials: S
authors.lastname: De Jaegere
authors.forename: L
authors.initials: L
authors.lastname: Nelles
authors.forename: R
authors.initials: R
authors.lastname: Casteels
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D000252:Calcium-Transporting ATPases; D004721:Endoplasmic Reticulum / Q000201:enzymology*; D007527:Isoenzymes; D008969:Molecular Sequence Data; D009130:Muscle, Smooth / Q000201:enzymology* / Q000648:ultrastructure; D013552:Swine
chemical_list: D007527:Isoenzymes; D000252:Calcium-Transporting ATPases