Lactase-like protein (LCTL)

Lactase-like protein (LCTL) is an atypical glycosidase enzyme and a member of the Klotho protein family, encoded by the LCTL gene. It is structurally similar to family 1 glycosidases but lacks one of the conserved glutamic acid residues necessary for typical catalytic activity, which likely limits or alters its enzymatic function[1][3]. LCTL is highly expressed in lens epithelial cells, especially in the equatorial germinative/differentiation zone, and is essential for normal lens suture organization and the expression of Clic5, a protein crucial for fiber cell extension and lens transparency[2][5]. Knockout of LCTL in mice leads to disorganized lens sutures, focusing defects, and age-related cataracts. Beyond ocular roles, LCTL may regulate cell proliferation and survival signaling, with studies linking it to modulation of FGF pathways in epithelial cells and a pro-survival role in certain triple-negative breast cancers by protecting against oxidative stress[1][2]. Alternative names like KLPH, γKlotho, and klotho-related protein reflect its relationship to other Klotho family members, but its precise physiological substrates and systemic functions remain partially unresolved. There are currently no known drugs directly targeting LCTL, and its therapeutic targeting is still under exploration, especially in oncology and ocular disease[1][2][3][5].

Other names

Klotho/lactase-phlorizin hydrolase-related proteinKLPHKLGγKlothogammaklothoklotho gammaFLJ33279UNQ3022/PRO9820KL lactase phlorizin hydrolase