TY - JOUR
T1 - Characterization of a cDNA encoding the 43-kDa membrane-associated inositol-polyphosphate 5-phosphatase
AU - Laxminarayan, Kamanoor M.
AU - Chan, Benedict K.
AU - Tetaz, Timothy
AU - Bird, Phillip I.
AU - Mitchell, Christina A.
PY - 1994/6/24
Y1 - 1994/6/24
N2 - Agonist stimulation of cells results in phosphatidylinositol turnover and the generation of inositol 1,4,5-trisphosphate (Ins(1,4,5)P3), which mobilizes intracellular calcium. The inositol-polyphosphate 5-phosphatase (5- phosphatase) enzymes hydrolyze Ins(1,4,5)P3 in a signal-terminating reaction. We have isolated a 2.7-kilobase (kb) composite cDNA, encoding the 43-kDa membrane-associated 5-phosphatase, by screening a human placental λgt11 library, using degenerate oligonucleotides. The 2.7-kb cDNA contains a 1.1-kb open reading frame, comprising 363 amino acids, which encodes a protein of a predicted molecular mass of 42 kDa. Amino acid sequence analysis demonstrates a number of potential sites for phosphorylation by protein kinase C and a CAAX motif in the COOH terminus, which may mediate membrane localization. The recombinant enzyme was expressed in COS-7 cells, resulting in a 50-fold increase in enzyme activity in the detergent-soluble membrane fraction of the cell (nanomole of Ins(1,4,5)P3 hydrolyzed per min/mg), but only a 2.5-fold increase in 5-phosphatase activity in the total cell homogenate. Sequence analysis demonstrated a 73-amino acid domain in the COOH terminus of the 43-kDa membrane-associated 5-phosphatase, which had 30% sequence identity and 67% similarity to a region in the 75-kDa 5-phosphatase and 34% identity and 70% similarity to a sequence in the protein that is encoded by the gene, defective in Lowe's oculocerebrorenal syndrome. As shown by RNA analysis the 43-kDa membrane-associated 5-phosphatase appears to be predominantly expressed in heart, brain, and skeletal muscle.
AB - Agonist stimulation of cells results in phosphatidylinositol turnover and the generation of inositol 1,4,5-trisphosphate (Ins(1,4,5)P3), which mobilizes intracellular calcium. The inositol-polyphosphate 5-phosphatase (5- phosphatase) enzymes hydrolyze Ins(1,4,5)P3 in a signal-terminating reaction. We have isolated a 2.7-kilobase (kb) composite cDNA, encoding the 43-kDa membrane-associated 5-phosphatase, by screening a human placental λgt11 library, using degenerate oligonucleotides. The 2.7-kb cDNA contains a 1.1-kb open reading frame, comprising 363 amino acids, which encodes a protein of a predicted molecular mass of 42 kDa. Amino acid sequence analysis demonstrates a number of potential sites for phosphorylation by protein kinase C and a CAAX motif in the COOH terminus, which may mediate membrane localization. The recombinant enzyme was expressed in COS-7 cells, resulting in a 50-fold increase in enzyme activity in the detergent-soluble membrane fraction of the cell (nanomole of Ins(1,4,5)P3 hydrolyzed per min/mg), but only a 2.5-fold increase in 5-phosphatase activity in the total cell homogenate. Sequence analysis demonstrated a 73-amino acid domain in the COOH terminus of the 43-kDa membrane-associated 5-phosphatase, which had 30% sequence identity and 67% similarity to a region in the 75-kDa 5-phosphatase and 34% identity and 70% similarity to a sequence in the protein that is encoded by the gene, defective in Lowe's oculocerebrorenal syndrome. As shown by RNA analysis the 43-kDa membrane-associated 5-phosphatase appears to be predominantly expressed in heart, brain, and skeletal muscle.
UR - http://www.scopus.com/inward/record.url?scp=0028227864&partnerID=8YFLogxK
M3 - Article
C2 - 8006039
AN - SCOPUS:0028227864
SN - 0021-9258
VL - 269
SP - 17305
EP - 17310
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 25
ER -