This domain found in the HPS3 protein is composed a an alpha solenoid repeat. This region carries a number of tyrosine sorting motifs and the second of two di-leucine sorting boxes at residues 711-717 well as the ER membrane-retention signal KKPL at residues 1000-1003 in SwissProt:Q969F9. There is also reference to a human Mendelian disease at MIM:614072 [1]. Mutations in the gene that encode this protein causes Hermansky-Pudlak syndrome 3 (HPS3), a genetically heterogeneous autosomal recessive disorder characterised by oculocutaneous albinism, a bleeding diathesis due to the absence of platelet dense granules and lysosomal storage defects [2].

1: Mutation of a new gene causes a unique form of Hermansky-Pudlak syndrome in a genetic isolate of central Puerto Rico. Anikster Y, Huizing M, White J, Shevchenko YO, Fitzpatrick DL, Touchman JW, Compton JG, Bale SJ, Swank RT, Gahl WA, Toro JR; Nat Genet. 2001;28:376-380. PMID:11455388

2: Hermansky-Pudlak syndrome type 3 in Ashkenazi Jews and other non-Puerto Rican patients with hypopigmentation and platelet storage-pool deficiency. Huizing M, Anikster Y, Fitzpatrick DL, Jeong AB, D'Souza M, Rausche M, Toro JR, Kaiser-Kupfer MI, White JG, Gahl WA; Am J Hum Genet. 2001;69:1022-1032. PMID:11590544