2050 base-pairs DNA linear, starts at 30624573 and ends at 3064506 bp from pter with plus strand orientation. This gene contains 1 exon.

The transcription produces 1 spliced mRNA variant (NM_020982), 2139 bp.

Not found.

The transcription of this gene gives 1 spliced mRNA that encodes 1 protein isoform with 217 aa and 22848 Da of molecular weight.

Pituitary gland (71,08%), lung (14,44%), intestine (6,87%), eye (6,56%), and brain (1,05%).

This is a multi-pass membrane protein localized in the tight junction, cell membrane, cytoplasm and nucleus.

Claudin-9 belongs to the claudin family. Claudins constitute integral membrane proteins responsible for solute and electrolyte permeability of the tight junction that serve as a physical barrier to prevent solutes and water from passing freely through the paracellular space between epithelial or endothelial cell sheets. Tight junctions also play a critical role in maintaining cell polarity and signal transductions. Claudin-9 creates charge specific channels in the paracellular space, plays a major role in tight junction-specific obliteration of the intercellular space, through calcium-independent cell-adhesion activity, is required to preserve sensory cells in the hearing organ because claudin-9-defective tight junctions fail to shield the basolateral side of hair cells from the K+-rich endolymph. Its ion barrier function is essential in the cochlea, but appears to be dispensable in other organs. Is one of the entry cofactors for hepatitis C virus; it enables HCV entry into target cells just as efficiently as CLDN1.

The CLDN9 gene is conserved in chimpanzee, dog, cow, mouse, rat, dog, opossum, lizard and zebrafish.