Coatomer subunit beta

Coatomer subunit beta (COPB1) is a core component of the coatomer complex, a cytosolic protein machinery that mediates vesicular transport between the endoplasmic reticulum and Golgi apparatus (UniProt: P53618). The protein binds dilysine motifs on cargo and facilitates retrograde Golgi-to-ER transport, budding from Golgi membranes, and ER-Golgi intermediate compartment organization. COPB1 also regulates lipid homeostasis at lipid droplets, participates in autophagy, and modulates receptor trafficking and degradation.

COPB1 is expressed widely in mammalian tissues and functions centrally in secretory pathway organization. UniProt documents an association with Baralle-Macken syndrome (BARMACS), an autosomal recessive neurodevelopmental disorder marked by global developmental delay, intellectual disability, speech impairment, and early-onset cataracts (UniProt: P53618).

In Alzheimer's disease, COPB1 is upregulated in post-mortem AD brain relative to age-matched controls, with a mean log2 fold-change of 0.25 (Chaparral AD proteomics). This modest but consistent elevation suggests increased vesicular trafficking activity or compensatory responses in AD pathology, though the functional significance requires further investigation.