Human kidney kallikrein: cDNA cloning and sequence analysis.

The primary structure of human kidney kallikrein has been elucidated by molecular cloning and cDNA sequence analysis. Structural homology between mammalian glandular kallikreins permitted the isolation of several clones from a human kidney cDNA library where kallikrein sequences represented approximately 0.01% of the cDNA. Identity of the cloned sequence with the published amino-terminal sequence of human urinary kallikrein strongly implicates the kidney as a major source of this protein. The overall structure of the kidney enzyme is 67% homologous to that of the corresponding mouse kidney kallikrein and only 60-62% homologous to the other published mouse kallikrein sequences. Homology to the pancreatic kallikreins of pig and rat is 67% and 61%, respectively. As expected, the amino acids required for catalytic activity are conserved as is the Asp residue required for the kallikrein-type specificity. Southern blot analysis demonstrates the presence of a number of related sequences in human DNA, although these do not appear to be as numerous as those in the mouse genome. Several polymorphisms in the kallikrein genes were observed.