This enzyme complex catalyzes an intermediate step in methanogenesis, the formation of methyl-coenzyme M and tetrahydromethanopterin from coenzyme M and N5-methyl-tetrahydromethanopterin. 5-methyl-5,6,7,8-tetrahydromethanopterin + coenzyme M + 2 Na(+)(in) = 5,6,7,8-tetrahydromethanopterin + methyl-coenzyme M + 2 Na(+)(out) Composed of six different subunits.