Acts as a co-chaperone for the SNARE protein SNAP-25 (PubMed:22187053). Involved in the calcium-mediated control of a late stage of exocytosis (PubMed:20847230). Acts as a general chaperone in regulated exocytosis (By similarity). May have an important role in presynaptic function (By similarity). May be involved in calcium-dependent neurotransmitter release at nerve endings (By similarity). Homodimer (Probable). Interacts with the chaperone complex consisting of HSC70 and SGTA (PubMed:17034881, PubMed:20847230). Interacts with ZDHHC13 (via ANK repeats) (PubMed:25253725, PubMed:26198635). Interacts with ZDHHC17 (via ANK repeats) (PubMed:25253725, PubMed:26198635). Interacts with SYT1, SYT5 and SYT7, and with SYT9, forming a complex with SNAP25 (PubMed:20847230). The interaction with SYT9 is stimulated tenfold in presence of calcium (PubMed:20847230). The association with membranes is regulated by palmitoylation (By similarity). Colocalizes with insulin granules, when overexpressed in an islet cell line (PubMed:17034881). Formation of the chaperone complex DNAJC5/HSC70 is not regulated by phosphorylation (PubMed:20847230). Ser-10 phosphorylation induces an order-to-disorder transition triggering the interaction with Lys-58 (By similarity). This conformational switch modulates DNAJC5's cellular functions by reducing binding to syntaxin and synaptogamin without altering HSC70 interactions (By similarity). Palmitoylated (PubMed:17034881). Could be palmitoylated by DHHC3, DHHC7, DHHC15 and DHHC17 (By similarity). Palmitoylation occurs probably in the cysteine-rich domain and regulates DNAJC5 membrane attachment (PubMed:17034881). Defective SNAP-25 function, which causes neurodegeneration by impairing SNARE-complex assembly (PubMed:22187053).