Helix-hairpin model, membrane protein

Fig. 4.1. Topology, conservation, andRHPmotif oftheStel4poI5. cerevisiae. (A) Hydropathy plots predict six transmembrane segments (TMs). In this model, the N-and C-termini are disposed toward the cytosol. TM 5 and 6 are proposed to form a helix-turn-helix hehcal hairpin within the membrane [25]. Fifteen unique Icmt protein sequences were ahgned using ClustalW 2.0.1.1 [27]. The blue residues denote amino acid identity and the magenta residues denote amino acid similarity. The C-terminal portion of the enzyme (136-239) contains the majority of the identical amino acids. (B) Sequence of the RHP motif, a C-terminal consensus sequence common to Icmt enzymes, a number of bacterial open reading frames, and two phosphatidyl-ethanolamine methyltransferases. Numbers denote the amino acid position in Stel4p.

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