Isoform 4 of Leucine-rich repeat flightless-interacting protein 1

LRRFIP1 (Leucine-rich repeat flightless-interacting protein 1) is a 73 kDa protein encoded by the LRRFIP1 gene in humans (UniProt: Q32MZ4-4). The protein contains leucine-rich repeat domains and interacts with flightless family members, though specific molecular functions are not detailed in current UniProt records.

LRRFIP1 is expressed in human tissues but disease associations are not explicitly documented in UniProt. The protein's role in intracellular signaling or protein–protein interactions remains incompletely characterized in available databases.

This isoform is curated as relevant to Alzheimer's Disease (AD). Quantitative proteomics analysis of post-mortem AD brain tissue versus age-matched controls revealed LRRFIP1 isoform 4 is significantly downregulated (mean log2FC = −0.42, one subcellular fraction; Chaparral AD proteomics). This reduction in AD brain suggests a possible loss of protective or homeostatic function in neurodegeneration, though the functional consequence of decreased LRRFIP1 in AD pathology requires further investigation.