Feline leukemia virus subgroup C receptor subfamily of the Major Facilitator Superfamily of transporters
The Feline leukemia virus subgroup C receptor (FLVCR) subfamily is conserved in metazoans and is composed of two vertebrate members, FLVCR1 and FLVCR2. FLVCR1 is a heme transporter and it has two isoforms: 1 (or FLVCR1a), which exports cytoplasmic heme as well as coproporphyrin and protoporphyrin IX; and 2 (FLVCR1b), which promotes heme efflux from the mitochondrion to the cytoplasm. FLVCR2 functions as a heme importer as well as a transporter for a calcium-chelator complex that is important for growth and calcium metabolism. The FLVCR subfamily belongs to the Solute carrier 49 (SLC49) family of the Major Facilitator Superfamily (MFS) of transporters. MFS proteins are thought to function through a single substrate binding site, alternating-access mechanism involving a rocker-switch type of movement.
Feature 1:putative chemical substrate binding pocket [chemical binding site]
Evidence:
Comment:based on the structures of MFS transporters with bound substrates, substrate analogs, and/or inhibitors
Comment:since MFS proteins facilitate the transport of many different substrates including ions, sugar phosphates, drugs, neurotransmitters, nucleosides, amino acids, and peptides, the residues involved in substrate binding may not be strictly conserved among superfamily members
Comment:the substrate binding site or translocation pore has access to both sides of the membrane in an alternating fashion through a conformational change of the MFS transporter
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