As part of AP-5, a probable fifth adaptor protein complex it may be involved in endosomal transport. According to PubMed:20613862 it is a putative helicase required for efficient homologous recombination DNA double-strand break repair. Probably part of the adaptor protein complex 5 (AP-5) a tetramer composed of AP5B1, AP5M1, AP5S1 and AP5Z1. Interacts with ZFYVE26 and SPG11. By SDS-PAGE, 2 isoforms have been observed, the shorter seems to be predominantly nuclear and the longer is mostly cytoplasmic. The disease is caused by variants affecting the gene represented in this entry. Extended N-terminus.