Proposed model for the function of SPATC1L in maintaining the stability of the sperm head-tail junction. SPATC1L is localized to the centrosome in a round spermatid, but separated from the centrosome in an elongating seprmatid. Finally, SPATC1L is localized to the neck region close to the centriole in testicular sperm. SPATC1L acts through interactions with RIα to increase PKA activity, and thereby increases the phosphorylation of CAPZB and stability of F-actin responsible for the integrity of the head-tail junction. 