ArticleThe Biochemical journal1993
Purification and characterization of phosphoinositide-specific phospholipase C from bovine iris sphincter smooth muscle.
Article in The Biochemical journal, 1993. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 1 paper.
What it found
Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.
The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.
Who cites it
1 citing paper in PubMed, 17 citations in OpenAlex.
Corrections and comments
PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.
Authors and funding
3 authors at 1 institution in 1 country.
Funding
Abstract
Two forms (I and II) of phosphoinositide-specific phospholipase C (PLC) were purified from the cytosol of bovine iris sphincter by sequential chromatography on DEAE-Sepharose, EAH-Sepharose, heparin-Sepharose, Sephacryl S-200 gel filtration and Mono Q HR columns. The final step resulted in specific activities of PLC-I and PLC-II of 4.3 and 5.9 mumol of phosphatidylinositol (PI) cleaved/min per mg of protein, which represented up to 295-fold purification compared with that of the starting supernatant. The purified enzymes were further investigated for the presence of isoenzymes and characterized for molecular mass, substrate specificity, pH, Ca2+ requirements and kinetic parameters. Using monoclonal antibodies, PLC-I was identified as PLC-delta 1. The apparent molecular mass of PLC-I as determined by SDS/PAGE and gel filtration was 85 kDa. PLC-II contained an apparently invisible protein band that reacted with the antibody against PLC-gamma 1, and a major 109 kDa protein band that was not recognized by any of the PLC monoclonal antibodies. Further purification of PLC-II by size-exclusion h.p.l.c. resulted in elution of the enzyme activity as a single peak which corresponded to 109 kDa position. Again, this PLC activity was not recognized by any of the PLC monoclonal antibodies. However, the 109 kDa protein activity was recognized by a polyclonal antibody raised against a rat PLC-gamma 1 fragment (amino acids 1272-1287), thus suggesting that this protein is a proteolytic product of PLC-gamma 1. PLC-delta 1 and PLC-gamma 1 were identified in the supernatant fraction and PLC-beta 1 in the membrane fraction of the iris sphincter. Although immunologically different, the catalytic properties of PLC-I and PLC-II were quite similar. The Vmax and Km values for phosphatidylinositol 4,5-bisphosphate (PIP2) hydrolysis were three to five times greater than those for PI hydrolysis. Both forms preferred PIP and PIP2 over PI and both were inactive against phosphatidylcholine. With PIP2 as substrate, the optimal pH values for PLC-I and PLC-II were 6.5 and 7.5 respectively. Unlike PIP2, PI hydrolysis by both forms was dependent on the presence of free Ca2+. The maximal hydrolysis of PI and PIP2 by both forms occurred at 200 and 5 microM Ca2+ respectively. Incubation of the purified enzymes with the catalytic subunit of protein kinase A (PKA) and [gamma-32P]ATP resulted in increased phosphorylation of PLC-I and PLC-II, but it had no inhibitory effect on their enzyme activities.(ABSTRACT TRUNCATED AT 400 WORDS)
Indexed as
Identifiers
What Socratic holds
Registered trials
Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the Socratic graph.