NEET BIOLOGY

Detailed explanation-1: -Gap junctions are clusters of intercellular channels that allow direct diffusion of ions and small molecules between adjacent cells. The intercellular channels are formed by head-to-head docking of hexameric assemblies (connexons) of tetraspan integral membrane proteins, the connexins (Cx) (Goodenough et al. 1996).

Detailed explanation-2: -Gap junctions are communicating junctions composed of clusters of connexons that allow molecules smaller than about 1000 daltons to pass directly from the inside of one cell to the inside of the next.

Detailed explanation-3: -Gap junction channels are formed by a family of proteins, the connexins, which are expressed in most tissues of an organism. Gap junction channels between contacting cells allow the passage of ions and other small molecules between the cells and thereby synchronize cells both electrically and metabolically.

Detailed explanation-4: -Molecules that can pass between cells coupled by gap junctions include inorganic salts, sugars, amino acids, nucleotides, and vitamins but not large molecules such as proteins or nucleic acids. Gap junctions are crucial to the integration of certain cellular activities.

Detailed explanation-5: -Diffusion of inositol triphosphate between the neighboring cells through gap junctions resulting in release of calcium from calcium stores is considered to be the mechanism behind the signaling process [145].