Intracellular localization of phosphatidylcholine and phosphatidylethanolamine synthesis in cotyledons of cotton seedlings

Journal Article · Tue Jan 01 04:00:00 EST 1991 · Plant Physiology; (United States)

DOI:https://doi.org/10.1104/pp.95.1.69· OSTI ID:5741912

Chapman, K D; Trelease, R N ^[1]

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1. Arizona State Univ., Tempe (United States)

Subfractionation of clarified cotyledon homogenates of cotton (Gossypium hirsutum L.) seedlings on sucrose gradients revealed a single coincident peak of cholinephosphotransferase (CPT) and ethanolaminephosphotransferase (EPT) activities, which equilibrated with the main peak of Anti-mycin A-insensitive NADH: cytochrome c reductase (CCR) activity. The small percentage of CPT and EPT activities in glyoxysome-enriched pellets equilibrated with cytochrome c oxidase activity, not with catalase activity. Preincubation of microsomes in 0.2 millimolar MgCl{sub 2} followed by subfractionation on sucrose gradients resulted in peak CPT and EPT activities equilibrating with peak CCR activity at 24% (w/w) sucrose. Preincubation of microsomes with {sup 14}C-CCP choline (or {sup 14}C-CDPethanolamine) resulted in synthesis and incorporation of {sup 14}C-phosphatidylcholine (PC) (or {sup 14}C-phosphatidylethanolamine, PE) into membranes at the same density. Increasing the Mg{sup 2+} concentration to 2.0 millimolar facilitated binding of ribosomes and caused a concomitant shift in density (to 34% w/w sucrose) of peak CPT, EPT, and CCR activities. under these conditions, newly synthesized and incorporated {sup 14}C-PC (or PE) was recovered in these membranes. These results indicate that Er in cotyledons of germinated cotton seedlings is the primary subcellular site of PC and PE synthesis. This is similar to the situation in endosperm tissue but distinctly different from root and hypocotyl tissue where Golgi are a major subcellular site of PC and PE synthesis.

• OSTI ID: 5741912
• Journal Information: Plant Physiology; (United States), Journal Name: Plant Physiology; (United States) Vol. 95:1; ISSN 0032-0889; ISSN PLPHA
• Country of Publication: United States
• Language: English

Related Subjects

551001* -- Physiological Systems-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
BIOLOGICAL PATHWAYS
BIOSYNTHESIS
CARBON 14 COMPOUNDS
CARBON COMPOUNDS
COTTON PLANTS
DISTRIBUTION
ENZYME ACTIVITY
ENZYMES
ESTERS
ISOTOPE APPLICATIONS
LABELLED COMPOUNDS
LIPIDS
MAGNOLIOPHYTA
MAGNOLIOPSIDA
ORGANIC COMPOUNDS
ORGANIC PHOSPHORUS COMPOUNDS
OXIDOREDUCTASES
PHOSPHOLIPIDS
PHOSPHORUS-GROUP TRANSFERASES
PHOSPHOTRANSFERASES
PHYSIOLOGY
PLANTS
PROTEINS
SEEDLINGS
SUBCELLULAR DISTRIBUTION
SYNTHESIS
TRACER TECHNIQUES
TRANSFERASES