Okklyudin

The OCLN gene is located on the long (q) arm of chromosome 5 at position q13.1. It starts from 69492292 base pairs and extends to 69558104 base pairs, having a length of 65813 base pairs. As a result of alternative splicing , two isoforms are expressed ^[4] .

In the human structure, 9 domains are distinguished, divided into two groups. The first group combines 5 domains located intracellularly and extracellularly, and the second group combines 4 transmembrane domains. These 9 domains are as follows:

• N-terminal domain (66 amino acids)
• transmembrane domain 1 (23 amino acids)
• extracellular loop 1 (46 amino acids)
• transmembrane domain 2 (25 amino acids)
• intracellular loop (10 amino acids)
• transmembrane domain 3 (25 amino acids)
• extracellular domain 2 (48 amino acids)
• transmembrane domain 4 (22 amino acids)
• C-terminal domain (257 amino acids).

The C-terminal domain is necessary for the proper creation of tight junctions. It also interacts with several cytoplasmic proteins in the connective disk and signaling molecules responsible for cell survival, and its N-terminal domain is involved in compacted tight junctions. The extracellular loop of oklyudin is involved in the regulation of paracelular permeability, and the extracellular domain 2 is involved in localization by close contact.

Okklyudin is important for the functioning of close contacts. It determines the density of tight junctions and plays an important role in providing a barrier function.