MCOLN1 and mucolipidosis type IV: As a major lysosomal calcium-permeating ion channel, TRPML1 plays important roles in lysosomal function including ion transport, lysosomal trafficking, autophagy, and lysosomal exocytosis.108,134,145 Human mutants of TRPML1 are associated with type IV mucolipidosis, an early-onset neurodegenerative condition.