Biomaterial Database

Fine structural localization of acyltransferases. The monoglyceride and -glycerophosphate pathways in intestinal absorptive cells. 1971

J A Higgins, and R J Barrnett

A study of the fine structural localization of the acyltransferases of the monoglyceride and alpha-glycerophosphate pathways for triglyceride synthesis in the intestinal absorptive cell is reported. Glutaraldehyde-fixed tissue was found to synthesize diglyceride and triglyceride from monopalmitin and palmityl CoA, and parallel morphological studies showed the appearance of lipid droplets in the smooth endoplasmic reticulum of the absorptive cell. Glutaraldehyde-fixed tissue also synthesized triglyceride from alpha-glycerophosphate, although this enzyme system was more susceptible to fixation than the monoglyceride pathway acyltransferases. Cytochemical methods for the localization of free CoA were based (a) on the formation of the insoluble lanthanium mercaptide of CoA and (b) on the reduction of ferricyanide by CoA to yield ferrocyanide which forms an insoluble precipitate with manganous ions. By these methods the monoglyceride pathway acyltransferases were found to be located mainly on the inner surface of the smooth endoplasmic reticulum. The alpha-glycerophosphate pathway acyltransferases were localized mainly on the rough endoplasmic reticulum. Activity limited to the outer cisternae of the Golgi membranes occurred with both pathways. The possible organization of triglyceride absorption and chylomicron synthesis is discussed in view of these results.

UI	MeSH Term	Description	Entries
D007583	Jejunum	The middle portion of the SMALL INTESTINE, between DUODENUM and ILEUM. It represents about 2/5 of the remaining portion of the small intestine below duodenum.	Jejunums
D008854	Microscopy, Electron	Microscopy using an electron beam, instead of light, to visualize the sample, thereby allowing much greater magnification. The interactions of ELECTRONS with specimens are used to provide information about the fine structure of that specimen. In TRANSMISSION ELECTRON MICROSCOPY the reactions of the electrons that are transmitted through the specimen are imaged. In SCANNING ELECTRON MICROSCOPY an electron beam falls at a non-normal angle on the specimen and the image is derived from the reactions occurring above the plane of the specimen.	Electron Microscopy
D010169	Palmitic Acids	A group of 16-carbon fatty acids that contain no double bonds.	Acids, Palmitic
D002914	Chylomicrons	A class of lipoproteins that carry dietary CHOLESTEROL and TRIGLYCERIDES from the SMALL INTESTINE to the tissues. Their density (0.93-1.006 g/ml) is the same as that of VERY-LOW-DENSITY LIPOPROTEINS.	Chylomicron
D004386	Duodenum	The shortest and widest portion of the SMALL INTESTINE adjacent to the PYLORUS of the STOMACH. It is named for having the length equal to about the width of 12 fingers.	Duodenums
D004721	Endoplasmic Reticulum	A system of cisternae in the CYTOPLASM of many cells. In places the endoplasmic reticulum is continuous with the plasma membrane (CELL MEMBRANE) or outer membrane of the nuclear envelope. If the outer surfaces of the endoplasmic reticulum membranes are coated with ribosomes, the endoplasmic reticulum is said to be rough-surfaced (ENDOPLASMIC RETICULUM, ROUGH); otherwise it is said to be smooth-surfaced (ENDOPLASMIC RETICULUM, SMOOTH). (King & Stansfield, A Dictionary of Genetics, 4th ed)	Ergastoplasm,Reticulum, Endoplasmic
D005989	Glycerides	GLYCEROL esterified with FATTY ACIDS.	Acylglycerol,Acylglycerols
D005994	Glycerophosphates	Any salt or ester of glycerophosphoric acid.	Glycerolphosphate,Glycerophosphate,Calcium Glycerophosphate,Glycerolphosphates,Glycerophosphate, Calcium
D006651	Histocytochemistry	Study of intracellular distribution of chemicals, reaction sites, enzymes, etc., by means of staining reactions, radioactive isotope uptake, selective metal distribution in electron microscopy, or other methods.	Cytochemistry
D000042	Absorption	The physical or physiological processes by which substances, tissue, cells, etc. take up or take in other substances or energy.