CLPSL2

Colipase-like protein 2 (CLPSL2), secreted protein (~100 amino acids, ~10.8 kDa) with high homology to pancreatic colipase (CLPS). Member of colipase protein family characterized by disulfide-rich β-sheet fold. Contains hydrophobic signal peptide for secretion, multiple conserved cysteine residues forming disulfide bonds, and colipase-like domain. Unlike pancreatic colipase (synthesized in exocrine pancreas, acts in intestinal lumen for dietary fat digestion), CLPSL2 shows tissue-enriched expression pattern: predominantly expressed in male reproductive tract (epididymis, prostate, seminal vesicle) and also in breast glandular cells, sebaceous glands, and pancreatic endocrine cells. Functions as predicted enzyme cofactor/activator for lipid-hydrolyzing enzymes in extracellular fluids. By analogy to colipase (which binds pancreatic lipase at lipid-water interface and counteracts bile salt inhibition), CLPSL2 likely facilitates action of lipases in non-digestive contexts such as reproductive physiology and exocrine secretions. In epididymis and seminal fluid: may activate lipase acting on lipids in seminal plasma or sperm surface, contributing to sperm maturation and membrane remodeling. In mammary gland: potentially aids processing of milk fat. In sebaceous glands: may influence skin oil composition. Gene ontology annotations link to enzyme activator activity, lipid catabolic process, and digestion (reflecting homology to digestive colipase). No specific target enzyme or substrate confirmed experimentally - function inferred from sequence/structural similarity, co-expression patterns, and tissue distribution. Secreted to extracellular space via secretory pathway. Localizes to secretory vesicles before secretion. Present in glandular fluids where target lipase(s) operate. Conserved across mammals with orthologs in rodents and primates, suggesting evolutionarily maintained function. Represents specialized paralog of colipase gene family adapted for tissue-specific lipid metabolism outside classical gut digestion.