- gap junction
- gap junction n an area of contact between adjacent cells characterized by modification of the plasma membranes for intercellular communication or transfer of low molecular-weight substancesgap-junc·tion·al 'gap-.jəŋk-shən-əl, -shnəl adj
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a type of intercellular junction comprising a narrowed portion (about 3 nm) of the intercellular space that contains channels or pores (about 2 nm) composed of hexagonal arrays of membrane-spanning proteins around a central lumen (connexon) through which pass ions and small molecules such as most sugars, amino acids, nucleotides, vitamins, hormones, and cyclic AMP. In electrically excitable tissues, these gap junctions serve to transmit electrical impulses via ionic currents and are known as electrotonic synapses; they are present in such tissues as myocardial tissue and the central nervous system. Called also nexus.Gap junctions providing passageways between the interiors of adjacent cells. Each gap junction consists of two connexons stacked end-to-end, spanning the gap between the membranes, with each connexon comprising six protein subunits arranged around a central channel.
Medical dictionary. 2011.