Osteoblasts express the PMCA1b isoform of the plasma membrane Ca(2+)-ATPase.
We report here that osteoblasts and osteoblast-like osteosarcoma cells express PMCA1b, an alternatively spliced transcript of plasma membrane Ca(2+)-ATPase. Synthetic oligonucleotide pairs were designed based upon unique regions of the cDNA encoding known PMCA isoforms (PMCA1-3) and used as primers in PCR-mediated amplification of cDNA synthesized from ROS 17/2.8 osteosarcoma cell RNA. A product was observed only when PMCA1-specific primers were present; no products were seen with PMCA2 or PMCA3 primers unless cDNA synthesized from rat brain RNA was present. Examination of the cDNA encoding the C terminus of PMCA1 from ROS 17/2.8 cells revealed that the mRNA is spliced to yield the PMCA1b isoform, a Ca(2+)-ATPase containing a consensus phosphorylation site for cAMP-dependent protein kinase A and a modified calmodulin binding domain. PMCA1b was also detected in UMR-106-01 osteosarcoma cells and unpassaged primary rat calvarial osteoblasts. These results suggest that the regulation of osteoblast function by agents that act via cAMP-mediated pathways may involve alterations in the activity of the plasma membrane Ca(2+)-ATPase.
Meszaros
J G
JG
Department of Physiology and Cell Biology, University of Texas Medical School, Houston.
Karin
N J
NJ
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D000252:Calcium-Transporting ATPases / Q000096:biosynthesis* / Q000737:chemistry / Q000235:genetics; D002462:Cell Membrane / Q000201:enzymology; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D018076:DNA, Complementary / Q000235:genetics / Q000378:metabolism; D007527:Isoenzymes / Q000096:biosynthesis* / Q000737:chemistry / Q000235:genetics; D008969:Molecular Sequence Data; D010006:Osteoblasts / Q000201:enzymology*; D012516:Osteosarcoma / Q000201:enzymology; D010766:Phosphorylation; D016133:Polymerase Chain Reaction; D012313:RNA / Q000302:isolation & purification; D012326:RNA Splicing; D051381:Rats; D017386:Sequence Homology, Amino Acid; D014158:Transcription, Genetic; D014407:Tumor Cells, Cultured
D018076:DNA, Complementary; D007527:Isoenzymes; D012313:RNA; D017868:Cyclic AMP-Dependent Protein Kinases; D000252:Calcium-Transporting ATPases