Surfeit locus protein 4

Surfeit locus protein 4 (SURF4) is an endoplasmic reticulum cargo receptor that mediates the export of lipoproteins by recruiting cargo into COPII vesicles for secretion (UniProt: O15260). It functions as a cargo receptor for lipoproteins bearing APOB and APOA1, thereby regulating lipoprotein delivery and lipid homeostasis, and also promotes secretion of PCSK9 and erythropoietin.

SURF4 is involved in ER-Golgi intermediate compartment and Golgi architecture maintenance (UniProt: O15260). The protein plays a central role in lipid metabolism and protein secretion pathways. No non-AD disease associations are currently annotated in UniProt for this protein.

In Alzheimer's disease, SURF4 is upregulated in human post-mortem AD brain tissue compared to age-matched controls (Chaparral AD proteomics), with a mean log2 fold-change of 0.82 across measured subcellular fractions. This upregulation may reflect altered lipid metabolism or protein secretion dynamics in the AD brain, warranting further investigation into the functional significance of elevated SURF4 levels during neurodegeneration.