Occludin, also known as OCLN,'s a human gene. Occludin's a 65-kDa (504-amino acid polypeptide) integral plasma-membrane protein located specifically at tight junctions described for the first time in 1993 by S Tsukita. Structure According to its overall hydrophilicity, occludin appears to span the plasma membrane four times, forming two extracellular loops and exposing its NH2 and COOH terminus to the cytosol. Interaction of occludin with several cytoplasmic proteins of the junctional plaque has… (More on Occludin)