Transmembrane emp24 domain-containing protein 5

TMED5 (transmembrane emp24 domain-containing protein 5) is a 229-amino acid protein involved in vesicular protein trafficking within the early secretory pathway (UniProt: Q9Y3A6). It plays a role in maintaining Golgi apparatus structure and facilitating protein exchange between Golgi stacks during assembly, though it is not required for COPI-mediated retrograde transport.

TMED5 is expressed in human tissues and localizes to membrane compartments of the secretory pathway. The UniProt record lists no primary disease associations, but the protein's trafficking functions suggest relevance to cellular processes dependent on proper Golgi organization and protein secretion.

In Alzheimer's disease, TMED5 is significantly upregulated in post-mortem human brain tissue compared to age-matched controls (Chaparral AD proteomics). Analysis of TMT-labeled samples across four subcellular fractions (P2, P3, S2, S3) from DDA proteomics detected the protein in 2 fractions with a mean log2 fold-change of +0.57, indicating consistent elevation in AD brain. This upregulation may reflect compensatory or pathological alterations in secretory pathway function associated with neurodegeneration.