C2 domain-containing protein 5

C2CD5 (C2 domain-containing protein 5) is a calcium-dependent phospholipid-binding protein that facilitates insulin-stimulated glucose transport by promoting SLC2A4/GLUT4 translocation from intracellular storage vesicles to the plasma membrane in adipocytes (UniProt: Q86YS7). The protein's C2 domain enables membrane fusion events critical for glucose homeostasis.

While C2CD5 is not formally associated with disease in the UniProt curated knowledge base, it functions in metabolic pathways that intersect with neurobiological processes. Metabolic dysregulation, including impaired glucose transport and utilization, has been implicated in neurodegenerative contexts.

In Alzheimer's disease, C2CD5 is significantly downregulated in post-mortem brain tissue compared to age-matched controls (mean log2FC = −0.47), based on TMT-labeled quantitative proteomics across multiple subcellular fractions (Chaparral AD proteomics). This reduced expression may reflect altered metabolic capacity or vesicular trafficking defects in AD pathology, though the functional consequence of C2CD5 loss in neuronal contexts remains to be determined.