Figure 8
The 3D projection of the M2 transmembrane helix of the α1-subunit of Na/K-ATPase (center) compared to the corresponding hydrophobic cluster analysis (left) and its relationship to the lipid bilayer of the plasma membrane (right). The center projection illustrates the sequence L134 to A154 (Rat Primary accession # PO6685) written in the classical α-helix (3.6 amino acids per turn). The left projection indicates the hydrophobic cluster analysis [15] after unrolling the helix (see text) with the hydrophobic clusters circled. Filled diamonds indicate glycine, squares with a point (serine) or not (threonine), and C for cysteine. The right projection depicts a stylized crystal cartoon of a lipid bilayer containing phosphatidylcholine but no cholesterol. The cartoon is a RasMol image of a phosphatidylcholine bilayer published by E. Martz (see Methods). Green spheres represent water oxygens, blue represent lipid nitrogen, red represent lipid oxygen, and yellow represent lipid phosphorus.