Unconventional myosin-XVIIIa

Unconventional myosin-XVIIIa (MYO18A) is a large motor protein that links Golgi membranes to the cytoskeleton and participates in vesicle budding and membrane trafficking. The protein also modulates actomyosin retrograde flow during cell migration, regulates innate immune receptor trafficking on macrophages, and enhances natural killer cell cytotoxicity (UniProt: Q92614).

MYO18A functions in Golgi apparatus organization and intracellular vesicle transport, with additional roles in immune cell regulation and inflammatory suppression. It acts as a receptor for surfactant-associated protein A and facilitates pathogen clearance by alveolar macrophages.

In Alzheimer's disease, MYO18A is significantly downregulated in post-mortem AD brain tissue compared to age-matched controls (Chaparral AD proteomics). Across three subcellular fractions examined in a TMT-labeled proteomics study, the protein showed a mean log2 fold-change of −0.35, indicating reduced expression. This downregulation may reflect impaired vesicle trafficking and Golgi dysfunction characteristic of neurodegenerative pathology.