Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0086543 (cataract)
 29,165 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The plasma membrane calcium ATPase (PMCA) uses energy to pump calcium (Ca2+) ions out of the cytosol into the extracellular milieu, usually against a strong chemical gradient. This energy expenditure is necessary to maintain a relatively low intracellular net Ca2+ load. Mammals have four genes (ATP2B1-ATP2B4), encoding the proteins PMCA1 through PMCA4. Transcripts from each of these genes are alternatively spliced to generate several variant proteins that are in turn post-translationally modified in a variety of ways. Expressed ubiquitously and with some level of functional redundancy in most vital tissues, only one of the four genes--Atp2b2--has been causally linked through naturally occuring mutations to disease in mammals: specifically to deafness and ataxia in spontaneous mouse mutants. In humans, a missense amino acid substitution in PMCA2 modifies the severity of hearing loss. Targeted null mutations of the Atp2b1 and Atp2b4 genes in mouse are embryonic lethal and cause a sperm motility defect, respectively. These phenotypes point to complex human diseases like hearing loss, cardiac function and infertility. Changes in PMCA expression are associated with other diseases including cataract formation, carciniogenesis, diabetes, and cardiac hypertension and hypertrophy. Severity of these diseases may be affected by subtle changes in expression of the PMCA isoforms expressed in those tissues.
 ...
PMID:The plasma membrane calcium ATPase and disease. 1819 44

The plasma membrane calcium ATPase (PMCA) pump is the major mechanism by which calcium is removed from the lens. The aim of this study was to determine if mRNA and proteins levels of PMCA isoforms changed with age or lens opacity. mRNA was quantified using a quantitative real-time reverse transcription polymerase chain reaction assay (RT-PCR). PMCA protein levels were quantified using Western blot analysis. No PMCA mRNA or proteins were detected in human lens fiber cells. The mRNA and protein levels of PMCA1, 3 and 4 in the epithelium of cataractous lenses were similar to those of epithelium from age-matched clear lenses and were also the same in younger lenses. PMCA2 mRNA and protein levels were 1.6-2.5 times higher, respectively, in cataractous lenses compared to age-matched clear lenses. Elevated PMCA2 expression in cataractous lenses might be a compensatory mechanism to overcome higher intracellular calcium levels in cataract.
 ...
PMID:Plasma membrane Ca-ATPase isoform expression in human cataractous lenses compared to age-matched clear lenses. 1822 1