KLK1KLK15

KLK1KLK15 refers to the human kallikrein-related peptidase gene cluster that comprises 15 genes, KLK1 through KLK15, located on chromosome 19q13.3-13.4. The KLK genes encode secreted serine proteases of the kallikrein family. These enzymes are typically produced as inactive proenzymes (zymogens) and activated in the extracellular space by proteolytic cleavage. All KLKs share a trypsin-like catalytic domain and a catalytic triad of histidine, aspartate, and serine, enabling them to cleave specific peptide substrates.

Expression of KLK genes is tissue-specific and tightly regulated. KLK3, best known as prostate-specific antigen (PSA), is regulated by androgens in the prostate. Other KLKs are highly expressed in the skin (for example KLK5, KLK7, and KLK14) and in other glandular tissues. Regulation is further influenced by cytokines and hormonal signals, and the cluster shows considerable transcriptional complexity.

Functionally, KLKs participate in extracellular proteolysis and protease cascades, contributing to processes such as skin desquamation, maturation of the epidermal barrier, and semen liquefaction. They can activate or process other proteases and growth factors, thereby influencing tissue remodeling and signaling.

Clinical relevance is centered on their secreted nature and tissue specificity. KLKs, particularly KLK3 (PSA), are established biomarkers in cancer diagnostics. Dysregulated KLK expression has been associated with prostate, ovarian, breast, and skin cancers, among others, and KLK family members are investigated as potential diagnostic markers or therapeutic targets. Genetic variation within the KLK cluster may affect expression and disease risk, making KLK1KLK15 a focus for research into protease networks and cancer biology.