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Mycobacterium tuberculosis CorA-like subfamily This bacterial subfamily belongs to the Thermotoga maritima CorA (TmCorA)-like family of the MIT superfamily of essential membrane proteins involved in transporting divalent cations (uptake or efflux) across membranes. This subfamily includes the Mg2+ transporter Mycobacterium tuberculosis CorA (which also transports Co2+). Thermotoga maritima CorA forms funnel-shaped homopentamers, the tip of the funnel is formed from two C-terminal transmembrane (TM) helices from each monomer, and the large opening of the funnel from the N-terminal cytoplasmic domains. The GMN signature motif of the MIT superfamily occurs just after TM1, mutation within this motif is known to abolish Mg2+ transport by a related protein, Saccharomyces cerevisiae Alr1p. Natural variants in this signature sequence may be associated with the transport of different divalent cations. The functional diversity of the MIT superfamily may also be due to minor structural differences regulating gating, substrate selection, and transport.
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