Phosphatidylinositol 4,5-bisphosphate phospholipase C and phosphomonoesterase in Dunaliella salina membranes

Journal Article · Sat Jul 01 00:00:00 EDT 1989 · Plant Physiology; (USA)

DOI:https://doi.org/10.1104/pp.90.3.1115· OSTI ID:6968937

Einspahr, K J; Peeler, T C; Thompson, Jr, G A ^[1]

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1. Univ. of Texas, Austin (USA)

In comparison with other cell organelles, the Dunaliella salina plasma membrane was found to be highly enriched in phospholipase C activity toward exogenous ({sup 3}H)phosphatidylinositol 4,5-bisphosphate (PIP{sub 2}). Based on release of ({sup 3}H)inositol phosphates, the plasma membrane exhibited a PIP{sub 2}-phospholipase C activity nearly tenfold higher than the nonplasmalemmal, nonchloroplast bottom phase (BP) membrane fraction and 47 times higher than the chloroplast membrane fraction. The majority of phospholipase activity was clearly of a phospholipase C nature since over 80% of ({sup 3}H)inositol phosphates released were recovered as ({sup 3}H)inositol trisphosphate (IP{sub 3}). These results suggest a plausible mechanism for the rapid breakdown of PIP{sub 2} and phosphatidylinositol 4-phosphate (PIP) following hypoosmotic shock. The authors have also examined some of the in vitro characteristics of the plasma membrane phospholipase C activity and have found it to be calcium sensitive, reaching maximal activity at 10 micromolar free (Ca{sup 2+}). They also report here that 100 micromolar GTP{gamma}S stimulates phospholipase C activity over a range of free (Ca{sup 2+}). Together, these results provide evidence that the plasma membrane PIP{sub 2}-phospholipase C of D. salina may be subject to Ca{sup 2+} and G-protein regulation.

• OSTI ID: 6968937
• Journal Information: Plant Physiology; (USA), Vol. 90:3; ISSN 0032-0889
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
CELL MEMBRANES
ENZYME ACTIVITY
ALGAE
CALCIUM
HYDROLASES
INOSITOLS
PHOSPHOLIPIDS
TRACER TECHNIQUES
TRITIUM COMPOUNDS
ALKALINE EARTH METALS
CARBOHYDRATES
CELL CONSTITUENTS
ELEMENTS
ENZYMES
ESTERS
HYDROGEN COMPOUNDS
ISOTOPE APPLICATIONS
LIPIDS
MEMBRANES
METALS
MONOSACCHARIDES
ORGANIC COMPOUNDS
ORGANIC PHOSPHORUS COMPOUNDS
PLANTS
SACCHARIDES
550201* - Biochemistry- Tracer Techniques