SLC45

Solute carrier family 45 (SLC45) refers to a group of membrane transport proteins within the broader solute carrier (SLC) superfamily. Members are predicted to be multi-pass transmembrane proteins that facilitate the movement of solutes across cellular membranes in various tissues. The family is found across a range of eukaryotes, indicating an ancient and conserved role in cellular transport.

In humans, the best characterized member is SLC45A2, also known as membrane-associated transporter protein (MATP). SLC45A2 is expressed predominantly in melanocytes and retinal pigment epithelium, where it localizes to melanosomes, the organelles responsible for pigment production. It is believed to play a role in maintaining proper melanosome conditions, such as pH, which influence the activity of enzymes like tyrosinase that drive melanin synthesis. Mutations in SLC45A2 cause oculocutaneous albinism type 4 (OCA4), a recessive condition characterized by hypopigmentation of the skin, hair, and eyes and often accompanied by visual impairment.

Other members of the SLC45 family in humans are less well characterized, with limited information on their precise substrates and biological roles. They are generally predicted to be transporters with tissue-specific expression patterns, but their physiological functions remain to be fully defined.

Structurally, SLC45 proteins are predicted to contain multiple transmembrane domains and are related to other major facilitator superfamily transporters. Ongoing research aims to clarify substrate specificities, regulatory mechanisms, and the full range of tissues in which SLC45 proteins operate.