Amino acid sequence restriction in relation to proteolysis.
Distributions of amino acid residues in proteins show that proline is overrepresented in sequence positions following two basic residues ([Lys Arg]-[Lys Arg]), i.e. at sites similar to those susceptible to proteolytic cleavages of hormonal pro-forms. Conformational correlations further show that [Lys Arg]-[Lys Arg]-Pro sequences are often (8/11) not adjacent to elements of secondary structure, whereas the opposite applies to [Lys Arg]-[Lys Arg]-nonPro sequences (82/103 adjacent to elements of secondary structure). These distribution patterns from proteins in general also seem applicable in individual protein groups as demonstrated for some dehydrogenases. It appears possible that [Lys Arg]-[Lys Arg]-nonPro constitutes a restricted sequence in proteins, and that proline, in addition to elements of secondary structure, contributes a means of avoiding unacceptable proteolytic processings of proteins in general.
D000595:Amino Acid Sequence; D001120:Arginine / Q000378:metabolism; D004789:Enzyme Activation; D008239:Lysine / Q000378:metabolism; D010088:Oxidoreductases / Q000378:metabolism; D010447:Peptide Hydrolases / Q000378:metabolism*; D011392:Proline / Q000378:metabolism; D011487:Protein Conformation; D013329:Structure-Activity Relationship; D013379:Substrate Specificity
D001120:Arginine; D011392:Proline; D010088:Oxidoreductases; D010447:Peptide Hydrolases; D008239:Lysine