Amino acid sequence of porcine spleen cathepsin D light chain.

The complete amino acid sequence of the light chain of cathepsin D from porcine spleen has been determined. The light chain consists of a single polypeptide chain with 97 amino acid residues. The sequence is: (formula; see text) The molecular weight of the light chain was calculated from this sequence to be 10,548 (without carbohydrates). A single disulfide bond links two half-cystine residues between positions 46 and 53. A cysteine residue is located at position 27. The light chain sequence is extensively homologous to the NH2-terminal sequence of other aspartyl proteases. It shows a 59% identity with the sequence of mouse submaxillary gland renin and a 49% identity with that of porcine pepsin. A single glycosylation site is located at residue 70 of the cathepsin D light chain. This site corresponds to position 67 of pepsin by homology. The active site aspartyl residue, corresponding to Asp-32 of pepsin, is located at residue 33 in the cathepsin D light chain.