N-terminal signal sequence is required for cellular trafficking and hyaluronan-depolymerization of KIAA1199

•Expression of full-length KIAA1199 is essential for HA depolymerizing activity.•The cleavage of N-terminal 30 amino acids occurs in functionally matured KIAA1199.•The deletion of the N-terminal portion results in altered localization of KIAA1199.•The N-terminal 30 amino acids of KIAA1199 are indeed the cleavable signal sequence. Recently, we disclosed that KIAA1199-mediated hyaluronan (HA) depolymerization requires an acidic cellular microenvironment (e.g. clathrin-coated vesicles or early endosomes), but no information about the structural basis underlying the cellular targeting and functional modification of KIAA1199 was available. Here, we show that the cleavage of N-terminal 30 amino acids occurs in functionally matured KIAA1199, and the deletion of the N-terminal portion results in altered intracellular trafficking of the molecule and loss of cellular HA depolymerization. These results suggest that the N-terminal portion of KIAA1199 functions as a cleavable signal sequence required for proper KIAA1199 translocation and KIAA1199-mediated HA depolymerization.