title: Identification of the expressed form of human cytosolic phospholipase A2beta (cPLA2beta): cPLA2beta3 is a novel variant localized to mitochondria and early endosomes.
abstract: In this study, we identify the principal splice variant of human cytosolic phospholipase A(2)beta (cPLA(2)beta) (also known as Group IVB cPLA(2)) present in cells. In human lung, spleen, and ovary and in a lung epithelial cell line (BEAS-2B), cPLA(2)beta is expressed as a 100-kDa protein, not the 114-kDa form originally predicted. Using RNA interference, the 100-kDa protein in BEAS-2B cells was confirmed to be cPLA(2)beta. BEAS-2B cells contain three different RNA splice variants of cPLA(2)beta (beta1, beta2, and beta3). cPLA(2)beta1 is identical to the previously cloned cPLA(2)beta, predicted to encode a 114-kDa protein. However, cPLA(2)beta2 and cPLA(2)beta3 splice variants are smaller and contain internal deletions in the catalytic domain. The 100-kDa cPLA(2)beta in BEAS-2B cells is the translated product of cPLA(2)beta3. cPLA(2)beta3 exhibits calcium-dependent PLA(2) activity against palmitoyl-arachidonyl-phosphatidylethanolamine and low level lysophospholipase activity but no activity against phosphatidylcholine. Unlike Group IVA cPLA(2)alpha, cPLA(2)beta3 is constitutively bound to membrane in unstimulated cells, localizing to mitochondria and early endosomes. cPLA(2)beta3 is widely expressed in tissues, suggesting that it has a generalized function at these unique sites.
authors.affiliation: Program in Cell Biology, Department of Pediatrics, National Jewish Medical and Research Center, 1400 Jackson Street, Denver, CO 80206, USA.
authors.forename: Moumita
authors.initials: M
authors.lastname: Ghosh
authors.forename: Robyn
authors.initials: R
authors.lastname: Loper
authors.forename: Michael H
authors.initials: MH
authors.lastname: Gelb
authors.forename: Christina C
authors.initials: CC
authors.lastname: Leslie
mesh_terms: D017398:Alternative Splicing; D000595:Amino Acid Sequence; D011992:Endosomes / Q000378:metabolism*; D054513:Group IV Phospholipases A2; D006801:Humans; D008928:Mitochondria / Q000378:metabolism*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010713:Phosphatidylcholines / Q000737:chemistry; D010741:Phospholipases A / Q000737:chemistry*; D017434:Protein Structure, Tertiary; D012313:RNA / Q000737:chemistry; D011994:Recombinant Proteins / Q000737:chemistry; D017386:Sequence Homology, Amino Acid; D014018:Tissue Distribution
chemical_list: D010713:Phosphatidylcholines; D011994:Recombinant Proteins; D012313:RNA; D010741:Phospholipases A; D054513:Group IV Phospholipases A2