User:Cody Couperus/Sandbox 3

IntroductionIntroduction

Cathepsin D (CD) is an apartic acid protease generally found in the lysosome of cells, but is also found intracellularly, extracellularly, and in endosomes. Its pH optimum is at an acidic pH (4-6).

CD important for protein degradation, but many physiologically relavent functions have been idenfified.

It is a heterodimer, with a 14 kD light chain and 34 kD heavy chain, activated from Procathepsin D autocatalytically and with assistance from cysteine proteases. Between the two lobes is an extended active site that accomidates 8 residues. CD specificity is gained by active site preference for hydrophobic residues. At the base of the active site are the two aspartate residues involved in catalysis of peptide bonds.