Adaptin

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Adaptin (AP) are proteins which mediate the formation of vescicles by clathrin-coated pits.

The AP-2 complex is a heterotetramer composed a core domain containing 2 large AP: AP-α or AP-γ and AP-β, a medium-size AP: AP-μ and small AP: AP-σ, 2 appendage domains or EAR. The core domain binds to the membrane and to cargo proteins which should be internalized and the EAR domains bind to clathrin and accessory proteins. There are different AP complexes in mammals.[1]

The AP-1 complex heterotetramer μ subunit packages insulin receptor substrates into clathrin-coated vescicles. This is needed for insulin/insulin-like growth factor bioactivities including mitogenesis[2].

The AP-3 complex heterotetramer is involved in the biogenesis of lysosome-related organelles[3]. It contains subunits β3, μ3, δ and σ3[4].

The AP-4 complex heterotetramer is involved in the targeting proteins from the trans-Golgi network (TGN) to yhr endosomal-lysosomal system. It contains subunits β-type, μ-type, ε and σ-type[5].

3D structures of adaptin

Adaptin 3D structures


Structure of Adaptin core: AP-α-2 (cyan), AP-β-1 (magenta), AP-μ-1 (green), AP-σ-1 (olive) complex with inositole hexakisphosphate (PDB entry 2vgl)

Drag the structure with the mouse to rotate


ReferencesReferences

  1. 1.0 1.1 Collins BM, McCoy AJ, Kent HM, Evans PR, Owen DJ. Molecular architecture and functional model of the endocytic AP2 complex. Cell. 2002 May 17;109(4):523-35. PMID:12086608
  2. Yoneyama Y, Matsuo M, Take K, Kabuta T, Chida K, Hakuno F, Takahashi S. The AP-1 complex regulates intracellular localization of insulin receptor substrate 1, which is required for insulin-like growth factor I-dependent cell proliferation. Mol Cell Biol. 2013 May;33(10):1991-2003. doi: 10.1128/MCB.01394-12. Epub 2013, Mar 11. PMID:23478262 doi:http://dx.doi.org/10.1128/MCB.01394-12
  3. Lefrancois S, Janvier K, Boehm M, Ooi CE, Bonifacino JS. An ear-core interaction regulates the recruitment of the AP-3 complex to membranes. Dev Cell. 2004 Oct;7(4):619-25. doi: 10.1016/j.devcel.2004.08.009. PMID:15469849 doi:http://dx.doi.org/10.1016/j.devcel.2004.08.009
  4. Simpson F, Peden AA, Christopoulou L, Robinson MS. Characterization of the adaptor-related protein complex, AP-3. J Cell Biol. 1997 May 19;137(4):835-45. doi: 10.1083/jcb.137.4.835. PMID:9151686 doi:http://dx.doi.org/10.1083/jcb.137.4.835
  5. Takatsu H, Futatsumori M, Yoshino K, Yoshida Y, Shin HW, Nakayama K. Similar subunit interactions contribute to assembly of clathrin adaptor complexes and COPI complex: analysis using yeast three-hybrid system. Biochem Biophys Res Commun. 2001 Jun 22;284(4):1083-9. doi:, 10.1006/bbrc.2001.5081. PMID:11409905 doi:http://dx.doi.org/10.1006/bbrc.2001.5081

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