May play a role in lipid transport. Highly expressed in adult retina and testis with lower levels in cerebral cortex, kidney and epididymis. In the retina, strongly expressed in the ganglion cell layer and throughout the inner nuclear layer in amacrine and bipolar cells. Not expressed in the outer nuclear layer. In the testis, detected in the seminiferous tubules. Expressed in adult but not at postnatal day 1. In the seminiferous tubule, expressed in first layer capped spermatids at stage VII and in spermatids closer to the lumen of the tubule at stage XII. Not detected in spermatogonia, first layer of spermatocytes or mature spermatozoa. Belongs to the calycin superfamily. Fatty-acid binding protein (FABP) family.