Proteases are enzymes that are involved in protein catabolism by hydrolyzing the peptide bonds between amino acids in a polypeptide chain. MPND (MPN domain-containing protein) is a 471 amino acid protein that is thought to be a protease. Expressed as two isoforms produced by alternative splicing, MPND contains a JAMM motif and one MPN domain. The gene that encodes MPND maps to human chromosome 19, which consists of around 63 million bases with over 1,400 genes, making up over 2% of human genomic DNA. Chromosome 19 includes a diversity of interesting genes and is recognized for having the greatest gene density of the human chromosomes. It is the genetic home for a number of immunoglobulin superfamily members including the killer cell and leukocyte Ig-like receptors, a number of ICAMs, the CEACAM and PSG family and Fcα receptors. Key genes for eye color and hair color also map to chromosome 19.