Indicate whether each of the following descriptions better applies to adherens junctions (A), desmosomes (D), gap junctions (G), or tight junctions (T). Your answer would be a four-letter string composed of letters A, D, G, and T only, e.g. AAAD.
( ) They play a direct role in structural polarization of epithelial cells.
( ) They couple cells both electrically and metabolically.
( ) They are formed from hexameric hemichannels that can assemble into heterotypic complexes.
( ) They create semipermeable paracellular pores.