Charged multivesicular body protein 1b

Charged multivesicular body protein 1b (CHMP1B) is a component of the ESCRT-III complex involved in multivesicular body formation and endosomal cargo sorting (UniProt: Q7LBR1). It mediates membrane invagination and intraluminal vesicle formation, processes critical for delivery of cargo to lysosomes. The protein also participates in cytokinesis and enveloped virus budding through its interactions with VPS4 and other ESCRT machinery components.

CHMP1B functions primarily in endosomal trafficking pathways that regulate lysosomal degradation of membrane proteins and lipids. No UniProt-curated disease associations are documented for this protein outside of the experimental evidence presented here.

In Alzheimer's disease, CHMP1B is significantly downregulated in post-mortem human brain tissue compared to age-matched controls, with a mean log2 fold-change of −0.44 (Chaparral AD proteomics). This downregulation was observed across a single subcellular fraction in a TMT-labeled proteomics study of four brain fractions, suggesting potential impairment of endosomal-lysosomal trafficking capacity in the AD brain.