Proteolytic processing sites producing the mature form of human cathepsin D.
1. The proteolytic processing sites of human lysosomal aspartic protease cathepsin D at which the intermediate single-chain form was converted into the mature two-chain form were determined. 2. The two chains were isolated by reversed-phase HPLC in order to investigate the cleavage sites of the enzyme. 3. Protein sequencing of the heavy chain, which was presumed to be derived from the C-terminal side in the single-chain enzyme, gave an N-terminal Leu 105. In addition, it revealed that there were also minor sequences, which commenced with Gly 106 and Gly 107. 4. A small C-terminal peptide was isolated from the light chain, which had been digested with two kinds of exogenous proteases. Sequence determination of this peptide, which was characterized as a nonapeptide by mass spectrometry, suggested that the C-terminus of the light chain was Ser 98. 5. These results indicate that a Ser 98-Ala 99 bond and an Ala 104-Leu 105 bond are cleaved to release 6 amino acid residues between the two chains.
Kobayashi
T
T
Biochemistry Laboratory, Hokkaido University School of Medicine, Sapporo, Japan.
Honke
K
K
Gasa
S
S
Fujii
T
T
Maguchi
S
S
Miyazaki
T
T
Makita
A
A
D000595:Amino Acid Sequence; D002402:Cathepsin D / Q000737:chemistry / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D006801:Humans; D008969:Molecular Sequence Data; D011499:Protein Processing, Post-Translational; D016339:Spectrometry, Mass, Fast Atom Bombardment
D002402:Cathepsin D