GRIP1-associated protein 1

GRIPAP1 (GRIP1-associated protein 1), also known as GRASP-1, is a scaffolding protein that regulates endosomal trafficking and synaptic signaling (UniProt: Q4V328). It localizes recycling endosomes to dendritic spines and facilitates AMPA receptor trafficking to dendritic membranes, supporting long-term potentiation and synaptic plasticity. Additionally, GRIPAP1 acts as a scaffold protein that promotes MAP3K1/MEKK1-mediated JNK1 kinase activation, linking it to stress-responsive signaling pathways.

These functions position GRIPAP1 at the intersection of synaptic maintenance and stress response in neurons. The protein's role in receptor recycling and dendritic spine organization suggests involvement in glutamatergic synaptic transmission and structural plasticity.

In Alzheimer's Disease, GRIPAP1 is significantly down-regulated in post-mortem AD brain tissue compared to age-matched controls (Chaparral AD proteomics, mean log2FC −0.43 across 2 subcellular fractions). This down-regulation may compromise endosomal recycling efficiency and synaptic receptor trafficking, potentially contributing to the synaptic dysfunction and plasticity deficits characteristic of AD pathology.