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X-Ray Diffraction Studies of Gap Junction Structure

1988; Elsevier BV; Volume: 2; Linguagem: Inglês

10.1016/s1569-2558(08)60432-4

1875-5291

Lee Makowski,

Mass Spectrometry Techniques and Applications

In this chapter, an attempt is made to reconcile the contradictory images of gap junctions observed by different experimental probes. The evidence for structure on the cytoplasmic surface of the junctions is reviewed, and its implications for the control of intercellular communication are discussed. The gap junction is composed of an array of morphological units that connect and span the cell membranes of two apposed cells. Most of the work reviewed in the chapter involves these isolated crystalline arrays of morphological units. As there is a high degree of homology among the amino-acid sequences of mammalian liver-gap junctions, the structures of mouse and rat liver-gap junctions are likely to be very similar. However, physiological, immunological, and structural studies of gap junctions from a broad range of tissues and species indicate substantial variety in the properties of junctions from different sources, presumably reflecting the variety of functions carried out by junctions in different tissues. Gap junctions are plaques ranging in size from a few morphological units to tens of thousands. In gap junctions from rodent livers, the connexon pairs can crystallize during the isolation procedure to form two-dimensional hexagonal lattices that constitute suitable specimens for detailed structural studies by X-ray diffraction and electron crystallography.