Recombinant Human MTNR1C protein

The MTNR1C protein, a member of the melatonin receptor family, belongs to the G protein-coupled receptor (GPCR) superfamily. While MTNR1A (MT1) and MTNR1B (MT2) are well-characterized receptors mediating melatonin's circadian and neuroendocrine effects, MTNR1C remains less studied. Initially identified as a pseudogene in humans due to sequence variations and lack of functional evidence, recent studies suggest its potential expression in specific tissues, though its physiological relevance is debated.

Recombinant MTNR1C protein is engineered for functional studies, typically expressed in heterologous systems like HEK293 or insect cells. Its structural features include seven transmembrane domains and conserved motifs shared with MT1/MT2. but ligand-binding assays show weak or absent melatonin affinity. This raises questions about its role as a melatonin receptor or its possible involvement in non-canonical signaling pathways.

Research focuses on resolving its biological significance: Some evidence links MTNR1C to metabolic regulation and cancer progression via unclear mechanisms. Recombinant versions enable exploration of dimerization with MT1/MT2 receptors, potentially modulating their activity. Challenges persist in confirming endogenous expression and distinguishing it from cross-reactivity with other receptors.

Pharmaceutical interest lies in its atypical GPCR behavior, offering insights into receptor evolution and allosteric modulation. While not a direct drug target, MTNR1C recombinant protein serves as a tool to decode melatonin receptor complexity and expand understanding of GPCR diversity. Further studies are needed to clarify its cellular localization, signaling partners, and species-specific functional divergence.