Mu-crystallin (CRYM)

Mu-crystallin (CRYM) is a multifunctional NADPH-dependent protein highly expressed in the brain, muscle, prostate, and kidney, where it primarily serves as an intracellular thyroid hormone-binding protein regulating the bioavailability of triiodothyronine (T3)[1][3][4][5]. When not bound to T3, CRYM acts as a ketimine reductase that participates in the pipecolate (lysine degradation) pathway, reducing naturally occurring cyclic ketimines and impacting amino acid and sulfur metabolism[1][2][3][5][6]. Aberrant expression or mutations in CRYM are implicated in non-syndromic deafness (DFNA40), neuropsychiatric and neuromuscular disorders, metabolic disturbances, and certain cancers—notably prostate cancer[1][2][3]. Due to its central metabolic and regulatory roles, especially in modulating the local availability and actions of thyroid hormone, CRYM is studied both as a molecular biomarker and as a potential—but not yet drug-targeted—modulator in various clinical contexts[1][2][3][5].

Other names

Ketimine reductase mu-crystallinNADP-regulated thyroid-hormone-binding proteinthiomorpholine-carboxylate dehydrogenasethyroid-hormone-binding protein (THBP)DFNA40P2C/Pyr2C reductasemu-crystallin homolog