Linked Life Data

16332677

Source:http://linkedlifedata.com/resource/pubmed/id/16332677

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
6
pubmed:dateCreated
2006-2-7
pubmed:abstractText
Human secretory pathway Ca2+/Mn2+-ATPase (SPCA) 2 encoded by ATP2C2 is only expressed in a limited number of tissues, unlike the ubiquitously expressed SPCA1 pump (encoded by ATP2C1, the gene defective in Hailey-Hailey disease). It has not been determined whether there are significant functional differences between SPCA1 and SPCA2 pump enzymes. Therefore, steady-state and transient kinetic approaches were used to characterize the overall and partial reactions of the Ca2+ transport cycle mediated by the human SPCA2 enzyme upon heterologous expression in HEK-293 cells. The catalytic turnover rate of SPCA2 was found enhanced relative to SPCA1 pumps. SPCA2 displayed a very high apparent affinity for cytosolic Ca2+ (K0.5 = 0.025 microm) in activation of the phosphorylation activity but still 2.5-fold lower than that of SPCA1d. Our kinetic analysis traced both differences to the increased rate characterizing the E1 approximately PCa to E2-P transition of SPCA2. Moreover, the reduced rate of the E2 to E1 transition seems to contribute in determining the lower apparent Ca2+ affinity and the increased sensitivity to thapsigargin inhibition, relative to SPCA1d. SPCA2 also displayed a reduced apparent affinity for inorganic phosphate, which could be explained by the observed enhanced rate of the E2-P dephosphorylation. The insensitivity to modulation by pH and K+ concentration of the constitutively enhanced E2-P dephosphorylation of SPCA2 is similar to SPCA1d and possibly represents a novel SPCA-specific feature, which is not shared by sarco(endo)plasmic reticulum Ca2+-ATPases.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Feb
pubmed:issn
0021-9258
pubmed:author
pubmed:issnType
Print
pubmed:day
10
pubmed:volume
281
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
3182-9
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed-meshheading:16332677-Adenosine Triphosphatases, pubmed-meshheading:16332677-Animals, pubmed-meshheading:16332677-COS Cells, pubmed-meshheading:16332677-Ca(2+) Mg(2+)-ATPase, pubmed-meshheading:16332677-Calcium, pubmed-meshheading:16332677-Catalysis, pubmed-meshheading:16332677-Cell Line, pubmed-meshheading:16332677-Cercopithecus aethiops, pubmed-meshheading:16332677-Cytosol, pubmed-meshheading:16332677-DNA, Complementary, pubmed-meshheading:16332677-Dose-Response Relationship, Drug, pubmed-meshheading:16332677-Endoplasmic Reticulum, pubmed-meshheading:16332677-Humans, pubmed-meshheading:16332677-Hydrogen-Ion Concentration, pubmed-meshheading:16332677-Ionophores, pubmed-meshheading:16332677-Kinetics, pubmed-meshheading:16332677-Models, Chemical, pubmed-meshheading:16332677-Phosphorylation, pubmed-meshheading:16332677-Potassium, pubmed-meshheading:16332677-Protein Isoforms, pubmed-meshheading:16332677-Temperature, pubmed-meshheading:16332677-Thapsigargin, pubmed-meshheading:16332677-Time Factors, pubmed-meshheading:16332677-Transfection
pubmed:year
2006
pubmed:articleTitle
Dissection of the functional differences between human secretory pathway Ca2+/Mn2+-ATPase (SPCA) 1 and 2 isoenzymes by steady-state and transient kinetic analyses.
pubmed:affiliation
Laboratory of Physiology, Catholic University of Leuven, Campus Gasthuisberg O/N, Herestraat 49, Bus 802, B-3000 Leuven, Belgium.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't