Biomaterial Database

Isolation and characterization of gap junctions from Drosophila melanogaster. 1989

J S Ryerse

Department of Pathology, St. Louis University School of Medicine, Missouri 63104.

A procedure has been developed to isolate gap junction-enriched subcellular fractions from Drosophila. Crude membranes from larval homogenates were extracted with 1% N-lauroyl sarcosine in 6 M urea and the gap junctions were collected by centrifugation. The major proteins were separated by SDS PAGE and purified by electro-elution. Electron microscopy revealed structurally pleiomorphic gap junctions in the fractions which included (1) conventional, 16-18 nm-wide septalaminar, (2) collapsed, 13-15 nm-wide pentalaminar, (3) split, and (4) aggregated forms. The fractions contained five major proteins with apparent molecular weights of 18, 26, 36, 52 and 54 kD. Evidence based on (1) the degradation and aggregation behavior of the major proteins following electro-elution and reelectrophoresis, (2) immunological cross-reactivities by affinity-purified antibodies against the major proteins on immunoblots, and (3) immunofluorescent staining of presumptive gap junctions in Drosophila imaginal discs at the light-microscopic level and immunogold staining of purified gap junctions at the electron-microscopic level suggests that the major proteins are interrelated and of gap-junction origin.

UI	MeSH Term	Description	Entries
D007365	Intercellular Junctions	Direct contact of a cell with a neighboring cell. Most such junctions are too small to be resolved by light microscopy, but they can be visualized by conventional or freeze-fracture electron microscopy, both of which show that the interacting CELL MEMBRANE and often the underlying CYTOPLASM and the intervening EXTRACELLULAR SPACE are highly specialized in these regions. (From Alberts et al., Molecular Biology of the Cell, 2d ed, p792)	Cell Junctions,Cell Junction,Intercellular Junction,Junction, Cell,Junction, Intercellular,Junctions, Cell,Junctions, Intercellular
D007814	Larva	Wormlike or grublike stage, following the egg in the life cycle of insects, worms, and other metamorphosing animals.	Maggots,Tadpoles,Larvae,Maggot,Tadpole
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
D008970	Molecular Weight	The sum of the weight of all the atoms in a molecule.	Molecular Weights,Weight, Molecular,Weights, Molecular
D009419	Nerve Tissue Proteins		Proteins, Nerve Tissue,Tissue Proteins, Nerve
D004331	Drosophila melanogaster	A species of fruit fly frequently used in genetics because of the large size of its chromosomes.	D. melanogaster,Drosophila melanogasters,melanogaster, Drosophila
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D013347	Subcellular Fractions	Components of a cell produced by various separation techniques which, though they disrupt the delicate anatomy of a cell, preserve the structure and physiology of its functioning constituents for biochemical and ultrastructural analysis. (From Alberts et al., Molecular Biology of the Cell, 2d ed, p163)	Fraction, Subcellular,Fractions, Subcellular,Subcellular Fraction