4IKN

Crystal structure of adaptor protein complex 3 (AP-3) mu3A subunit C-terminal domain, in complex with a sorting peptide from TGN38

Summary for 4IKN

• Entry DOI: 10.2210/pdb4ikn/pdb
• Descriptor: AP-3 complex subunit mu-1, Trans-Golgi network integral membrane protein TGN38 (3 entities in total)
• Functional Keywords: immunoglobulin-like beta-sandwich, signal recognition, cytosolic tail of transmembrane proteins, adaptor protein, protein transport
• Biological source: Rattus norvegicus (brown rat,rat,rats); More
• Cellular location: Golgi apparatus: P53676; Golgi apparatus, trans-Golgi network membrane; Single-pass membrane protein (Potential): P19814
• Total number of polymer chains: 2
• Total formula weight: 30121.79

Authors

Mardones, G.A.,Kloer, D.P.,Burgos, P.V.,Bonifacino, J.S.,Hurley, J.H. (deposition date: 2012-12-26, release date: 2013-02-20, Last modification date: 2023-09-20)

Primary citation

Mardones, G.A.,Burgos, P.V.,Lin, Y.,Kloer, D.P.,Magadan, J.G.,Hurley, J.H.,Bonifacino, J.S.
Structural basis for the recognition of tyrosine-based sorting signals by the mu 3A subunit of the AP-3 adaptor complex.
J.Biol.Chem., 288:9563-9571, 2013

PubMed Abstract: Tyrosine-based signals fitting the YXXØ motif mediate sorting of transmembrane proteins to endosomes, lysosomes, the basolateral plasma membrane of polarized epithelial cells, and the somatodendritic domain of neurons through interactions with the homologous μ1, μ2, μ3, and μ4 subunits of the corresponding AP-1, AP-2, AP-3, and AP-4 complexes. Previous x-ray crystallographic analyses identified distinct binding sites for YXXØ signals on μ2 and μ4, which were located on opposite faces of the proteins. To elucidate the mode of recognition of YXXØ signals by other members of the μ family, we solved the crystal structure at 1.85 Å resolution of the C-terminal domain of the μ3 subunit of AP-3 (isoform A) in complex with a peptide encoding a YXXØ signal (SDYQRL) from the trans-Golgi network protein TGN38. The μ3A C-terminal domain consists of an immunoglobulin-like β-sandwich organized into two subdomains, A and B. The YXXØ signal binds in an extended conformation to a site on μ3A subdomain A, at a location similar to the YXXØ-binding site on μ2 but not μ4. The binding sites on μ3A and μ2 exhibit similarities and differences that account for the ability of both proteins to bind distinct sets of YXXØ signals. Biochemical analyses confirm the identification of the μ3A site and show that this protein binds YXXØ signals with 14-19 μm affinity. The surface electrostatic potential of μ3A is less basic than that of μ2, in part explaining the association of AP-3 with intracellular membranes having less acidic phosphoinositides.

PubMed: 23404500
DOI: 10.1074/jbc.M113.450775

Experimental method

X-RAY DIFFRACTION (1.851 Å)