Adaptor protein, phosphotyrosine interacting with PH domain and leucine zipper 1 (APPL1), or DCC-interacting protein 13-alpha (DIP13alpha), is a protein that in humans is encoded by the APPL1 gene. APPL1 contains several key interactory domains: pleckstrin homology (PH) domain, phosphotyrosine-binding (PTB) domain and Bin–Amphiphysin–Rvs (BAR) domain. APPL1 is an adaptor protein localized to a subset of Rab5-positive ("early") endosomes, where it recruits other binding partners and regulates vesicle trafficking and endosomal signalling. APPL1 is enriched at very early endosomes which are negative for EEA1, indicating that APPL1 affects the earliest stages of endosomal traffic before EEA1 takes over. This is in line with observations that APPL1 and EEA1 compete for Rab5 binding. APPL1 affects the speed of internalization of key endosomal cargo (eg. EGF receptor) which is dependent on Rab5 activation. PTB domain of APPL1 regulates many cell signalling events in specific endosomal compartments - sometimes termed the "signalling endosomes". This includes lysophosphatidic acid (LPA)-induced signaling (together with interacting protein GIPC1). Additional roles for APPL1 were pinpointed to the nucleus where APPL1 can localize once dissociated from endosomes.
Background References
1. Du Y et al. Dysfunctional APPL1-Mediated Epigenetic Regulation in Diabetic Vascular Injury. Arterioscler Thromb Vasc Biol. 2023 Dec
2. Artimani T et al. APPL1 as an important regulator of insulin and adiponectin-signaling pathways in the PCOS: A narrative review. Cell Biol Int. 2020 Aug
Western blot analysis of APPL on different lysates with Rabbit anti-APPL antibody (HA722430) at 1/1,000 dilution.
Lane 1: HeLa cell lysate Lane 2: MCF7 cell lysate Lane 3: HEK-293 cell lysate Lane 4: C2C12 cell lysate Lane 5: PC-12 cell lysate Lane 6: Mouse brain tissue lysate Lane 7: Rat lung tissue lysate
Lysates/proteins at 20 µg/Lane.
Predicted band size: 80 kDa Observed band size: 80 kDa
Exposure time: 15 seconds; ECL: K1801;
4-20% SDS-PAGE gel.
Proteins were transferred to a PVDF membrane and blocked with 5% NFDM/TBST for 1 hour at room temperature. The primary antibody (HA722430) at 1/1,000 dilution was used in 5% NFDM/TBST at 4℃ overnight. Goat Anti-Rabbit IgG - HRP Secondary Antibody (HA1001) at 1/50,000 dilution was used for 1 hour at room temperature.
Immunohistochemical analysis of paraffin-embedded human pancreas tissue with Rabbit anti-APPL antibody (HA722430) at 1/500 dilution.
The section was pre-treated using heat mediated antigen retrieval with Tris-EDTA buffer (pH 9.0) for 20 minutes. The tissues were blocked in 1% BSA for 20 minutes at room temperature, washed with ddH2O and PBS, and then probed with the primary antibody (HA722430) at 1/500 dilution for 1 hour at room temperature. The detection was performed using an HRP conjugated compact polymer system. DAB was used as the chromogen. Tissues were counterstained with hematoxylin and mounted with DPX.
Immunohistochemical analysis of paraffin-embedded mouse pancreas tissue with Rabbit anti-APPL antibody (HA722430) at 1/500 dilution.
The section was pre-treated using heat mediated antigen retrieval with Tris-EDTA buffer (pH 9.0) for 20 minutes. The tissues were blocked in 1% BSA for 20 minutes at room temperature, washed with ddH2O and PBS, and then probed with the primary antibody (HA722430) at 1/500 dilution for 1 hour at room temperature. The detection was performed using an HRP conjugated compact polymer system. DAB was used as the chromogen. Tissues were counterstained with hematoxylin and mounted with DPX.
Immunohistochemical analysis of paraffin-embedded rat pancreas tissue with Rabbit anti-APPL antibody (HA722430) at 1/500 dilution.
The section was pre-treated using heat mediated antigen retrieval with Tris-EDTA buffer (pH 9.0) for 20 minutes. The tissues were blocked in 1% BSA for 20 minutes at room temperature, washed with ddH2O and PBS, and then probed with the primary antibody (HA722430) at 1/500 dilution for 1 hour at room temperature. The detection was performed using an HRP conjugated compact polymer system. DAB was used as the chromogen. Tissues were counterstained with hematoxylin and mounted with DPX.
APPL was immunoprecipitated from 0.2 mg HEK-293 cell lysate with HA722430 at 2 µg/10 µl beads. Western blot was performed from the immunoprecipitate using HA722430 at 1/1,000 dilution. HRP Conjugated Anti-Rabbit IgG for IP Nano-secondary antibody at 1/5,000 dilution was used for 1 hour at room temperature.
Lane 1: HEK-293 cell lysate (input) Lane 2: HA722430 IP in HEK-293 cell lysate Lane 3: Rabbit IgG instead of HA722430 in HEK-293 cell lysate