vab-9 encodes a claudin homolog orthologous to human brain cell membrane protein 1 (BCMP1) and Drosophila CG6982; VAB-9 colocalizes with HMP-1 to an apical layer of the adherens junctions of all epithelial cells, one layer more apically than AJM-1; vab-9 mutants have disorganized F-actin at the adherens junction, implying that VAB-9 links junctions to circumferential actin filaments; VAB-9 is also expressed in the nerve ring; VAB-9 requires the cadherin HMR-1 to localize to the cell membrane, and both alpha-catenin (HMP-1) and beta-catenin (HMP-2) to remain at the cell junction after membrane localization.
Involved in cell-cell adhesion; defense response to Gram-negative bacterium; and innate immune response. Located in cell junction. Expressed in epithelial cell; hypodermis; and nerve ring. Human ortholog(s) of this gene implicated in erythrokeratodermia variabilis and mutilating palmoplantar keratoderma with periorificial keratotic plaques. Is an ortholog of human TMEM47 (transmembrane protein 47).