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.[8]
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.[8]
Mutant studies
Mouse Mutant Alleles for Appl1
Marker Symbol for Mouse Gene. This symbol is assigned to the genomic locus by the MGI
Example structure of targeted conditional mutant allele for this gene
These Mutant ES Cells can be studied directly or used to generate mice with this gene knocked out. Study of these mice can shed light on the function of Appl1:
^"Human PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
^"Mouse PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
^ abMitsuuchi Y, Johnson SW, Sonoda G, Tanno S, Golemis EA, Testa JR (September 1999). "Identification of a chromosome 3p14.3-21.1 gene, APPL, encoding an adaptor molecule that interacts with the oncoprotein-serine/threonine kinase AKT2". Oncogene. 18 (35): 4891–8. doi:10.1038/sj.onc.1203080. PMID10490823. S2CID25245749.
Rual JF, Venkatesan K, Hao T, Hirozane-Kishikawa T, Dricot A, Li N, Berriz GF, Gibbons FD, Dreze M, Ayivi-Guedehoussou N, Klitgord N, Simon C, Boxem M, Milstein S, Rosenberg J, Goldberg DS, Zhang LV, Wong SL, Franklin G, Li S, Albala JS, Lim J, Fraughton C, Llamosas E, Cevik S, Bex C, Lamesch P, Sikorski RS, Vandenhaute J, Zoghbi HY, Smolyar A, Bosak S, Sequerra R, Doucette-Stamm L, Cusick ME, Hill DE, Roth FP, Vidal M (October 2005). "Towards a proteome-scale map of the human protein-protein interaction network". Nature. 437 (7062): 1173–8. Bibcode:2005Natur.437.1173R. doi:10.1038/nature04209. PMID16189514. S2CID4427026.
Mao X, Kikani CK, Riojas RA, Langlais P, Wang L, Ramos FJ, Fang Q, Christ-Roberts CY, Hong JY, Kim RY, Liu F, Dong LQ (May 2006). "APPL1 binds to adiponectin receptors and mediates adiponectin signalling and function". Nature Cell Biology. 8 (5): 516–23. doi:10.1038/ncb1404. PMID16622416. S2CID21273764.
