Amino acid sequence of the ribonuclease inhibitor from porcine liver reveals the presence of leucine-rich repeats.
The primary structure of the ribonuclease inhibitor from pig liver has been determined by amino acid sequence analysis. The N alpha-acetylated polypeptide chain of 456 amino acids consists of 15 homologous leucine-rich repeats, characterized by leucyl residues at constant positions. Two types of alternating repeats occur, 29 (A) and 28 (B) residues long. The degree of identity between repeats of a given type ranged from 25 to 60%. Only one deletion in the B-repeat was necessary to perfectly align the leucyl residues between the two repeats. Leucine-rich repeats have previously been found in four membrane-bound proteins and one extracellular protein, and their amphiphilic character suggested that they could be involved in membrane binding. Ribonuclease inhibitor is the first example of a cytoplasmic protein containing this type of repeat. It seems likely, therefore, that leucine-rich repeats can have functions other than forming membrane binding structures.
Hofsteenge
J
J
Friedrich Miescher Institut, Basel, Switzerland.
Kieffer
B
B
Matthies
R
R
Hemmings
B A
BA
Stone
S R
SR
D000595:Amino Acid Sequence; D000818:Animals; D003488:Cyanogen Bromide; D004791:Enzyme Inhibitors / Q000235:genetics* / Q000302:isolation & purification; D007930:Leucine; D008099:Liver / Q000378:metabolism*; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000032:analysis; D011506:Proteins / Q000235:genetics* / Q000302:isolation & purification; D012260:Ribonucleases / Q000037:antagonists & inhibitors*; D012689:Sequence Homology, Nucleic Acid; D012697:Serine Endopeptidases; D013552:Swine; D014357:Trypsin
D004791:Enzyme Inhibitors; D010446:Peptide Fragments; D011506:Proteins; D012260:Ribonucleases; D012697:Serine Endopeptidases; C028344:glutamyl endopeptidase; D014357:Trypsin; D007930:Leucine; D003488:Cyanogen Bromide