FKBP15-2 Antibody

Overview of FKBP15 and Its Isoforms

FKBP15 (UniProt ID: Q5T1M5 in humans) is a 133 kDa immunophilin initially identified as a target for immunosuppressants like FK506 and rapamycin . It contains a WASP homology region 1 (WH1) domain and modulates cytoskeletal organization in neuronal growth cones . Three isoforms are documented, though their specific designations (e.g., FKBP15-1, -2, -3) remain unclear in public databases . Antibodies against FKBP15 typically recognize epitopes shared across isoforms unless specified.

Research Applications and Findings

A. Neuronal Development
FKBP15 co-localizes with F-actin in growth cones of dorsal root ganglion neurons. Overexpression increases filopodia density, suggesting a role in axonal guidance . Antibodies like PA5-115237 (Thermo Fisher) have been used to validate these findings via immunocytochemistry .

B. Endosomal Transport
RNAi-mediated FKBP15 knockdown delays early endosome transport in HeLa cells . Western blot (WB) studies using ab14432 (Abcam) confirmed FKBP15’s association with microtubules and actin filaments .

C. Subcellular Localization
FKBP15 is primarily cytoplasmic but also detected in the cytosol and nucleus. The Human Protein Atlas reports antibody validation in U2OS and HeLa cells .

Validation and Cross-Reactivity

• Specificity: Antibodies such as PA5-52495 (Thermo Fisher) show 95% sequence homology with mouse FKBP15 and 94% with rat .

• Controls: Negative WB results in NIH/3T3 cells (ab14432) highlight the importance of optimizing antibody concentrations for specific cell lines.

Limitations and Considerations

• No commercial antibodies explicitly distinguish between FKBP15 isoforms.

• Some antibodies (e.g., NB100-424) are unsuitable for WB but effective in IP .

• Batch variability necessitates validation using knockout controls .

Future Directions

Further isoform-specific antibody development is critical to dissect FKBP15’s roles in diseases like neurodegeneration. Current tools remain foundational for studying its interactions with cytoskeletal regulators .