Plays a role in actin regulation at the ectoplasmic specialization, a type of cell junction specific to testis. Important for establishment of sperm polarity and normal spermatid adhesion. May also promote integrity of Sertoli cell tight junctions at the blood-testis barrier. Interacts with PALLD (By similarity). Associates with actin (PubMed:11168586). However, does not bind F-actin directly (PubMed:11168586). Associated with the cortical actin cytoskeleton structures in terminal web and cell-cell adhesion sites (PubMed:11168586). Highly expressed at the ectoplasmic specialization, an actin-rich cell junction specific to the testis (By similarity). Predominantly nuclear in nonconfluent cells (By similarity). Highly expressed in testis, where it localizes to seminiferous tubules (at protein level) (PubMed:11042181, PubMed:16806700). Expressed in ganglion cell layer and in Muller cell fibers of the retina (at protein level) (PubMed:11042181, PubMed:16806700). In small intestine highly expressed at the apical and lateral borders of absorptive epithelia (at protein level) (PubMed:11168586). In liver highly expressed along the bile canaliculi (at protein level) (PubMed:11168586). At 9.5 days, expression is detected in branchial arch mesenchyme, forebrain, hindbrain, midbrain, and neural tube. At 12.5 days, is detected in the hindbrain, forebrain, lung, genital eminence, spinal ligaments around vertebrae and ribs, and around the cartilage of ribs and nasal sinuses. Also detected in frontonasal mass, mandibular arch, optic sulcus, spinal ganglia and hind limb bud. At 15.5 days, expression is detected in the ventricular layer of neurons subjacent to the neocortex, around the nasal sinuses, bronchioles of the lung, kidney, and around the vertebrae of the tail. Also seen in the olfactory bulb.