This domain is found in Methyl-accepting chemotaxis sensory transducer, class 40H from Geobacter sulfurreducens (Mcp40H-20, Swiss:Q74EM7) and similar proteins predominantly from proteobacteria. This entry represents the periplasmic c-type heme-containing sensor domain, which is located between two transmembrane helices near the N terminus of the protein. This domain adopts a PAS-type domain fold with two helical segments followed by a four-stranded beta-sheet [1].

1: Structures and solution properties of two novel periplasmic sensor domains with c-type heme from chemotaxis proteins of Geobacter sulfurreducens: implications for signal transduction. Pokkuluri PR, Pessanha M, Londer YY, Wood SJ, Duke NE, Wilton R, Catarino T, Salgueiro CA, Schiffer M; J Mol Biol. 2008;377:1498-1517. PMID:18329666