Structural analysis of the Leu262Proβ₃mutation.

(A) Leucine (Leu) 262 is completely conserved among β subunits. The amino acid sequence of human β₃ residues cystine (Cys) 232 to Cys273 is shown aligned with frog (Xenopus) and mouse β₃ and with the sequences of 7 other human β subunits. Notably, the Leu residue at position 262 (in boldface) is invariant. The proposed intramolecular disulfide loop Cys232-27330is shown. (B) Predicted hydrophobicity and secondary structure are shown for β₃ amino acids 200 to 300 containing either wild-type Leu262 (black line) or mutant Pro262 (stippled line with arrow). The position of amino acid 262 is indicated by the vertical line.