Clathrin adaptor

COPI-coated vesicles mediate intra-Golgi transport and Golgi to ER retrograde transport. The coats of these vesicles do not show the geometric forms seen with clathrin coats and have a more complex protein composition [3]. Coat protein purification first lead to the identification of a complex composed of seven individual coat-protein subunits, known as COPI or coatomer. Some of these subunits bear a sequence similarity to clathrin adaptors. In addition, there is a small GTP-binding protein, Arfl, present on COPI-coated vesicles. 

Arrestin then interacts with clathrin and clathrin adaptor AP2, leading to endocytosis of the receptor. In addition to blunting responses requiring the presence of the receptor on the cell surface, these regulatory processes may also contribute to novel mechanisms of receptor signaling via intracellular pathways. 

The signal for the rapid internalization of MPR 300 at the plasma membrane has been localized to the pentapeptide KYSKV (residues 24-29 in its 163-residue cytoplasmic tail). MPR 46 appears to contain in its cytoplasmic tail of 67 residues several distinct signals for rapid internalization and binding to clathrin adaptors. Both receptors have a leucine-based sorting signal close to their C terminus, which is critical for their ability to sort lysosomal enzymes (Den-zer et al., 1997). 

Nakatsu F, Okada M, Mori F, Kumazawa N, Iwasa H, et al. 2004. Defective function of GABA-containing synaptic vesicles in mice lacking the AP-3B clathrin adaptor. J Cell Biol 167 293-302. 

Goodman OB Jr, Krupnick JG, Santini F et al (1996) Beta-arrestin acts as a clathrin adaptor in endocytosis of the beta2-adrenergic receptor. Nature 383 447-450... 

Crottet, P., Meyer, D. M., Rohrer, J., and Spiess, M. (2002). ARFl.GTP, tyrosine-based signals, and phosphatidylinositol 4,5-bisphosphate constitute a minimal machinery to recruit the AP I clathrin adaptor to membranes. Mol. Biol. Cell. 13, 3672-3682. 

Stamnes, M. A., and Rothman, J. E. (1993). The binding of AP-1 clathrin adaptor particles to Golgi membranes requires ADP-ribosylation factor, a small GTP-binding protein. Cell 73, 999-1005. 

We have previously shown that BIG2 is localized not only to the TGN but also to the punctate structures throughout the cytoplasm, where BIG2 is extensively colocalized with the AP-1 clathrin adaptor complex and the transferrin (Tfn) receptor (a marker for the EE and RE) but not with EEAl (a marker for the EE) or Lamp-1 (a marker for the LE and... 

Kirchhausen, T. (2002). Clathrin adaptors really adapt. Cell 109, 413-416. 

Smythe, E., Carter, L. L., and Schmid, S. L. (1992). Cytosol- and clathrin-dependent stimulation of endocytosis in vitro by purified adaptors. J. Cell Biol 119, 1163-1171. Traub, L. M. (2003). Sorting it out AP-2 and alternate clathrin adaptors in endocytic cargo selection. J. Cell Biol. 163, 203-208. 

Glickman, J. N., E. Conibear, and B. M. Pearse. 1989. Specificity of binding of clathrin adaptors to signals on the mannose-6-phosphate/insulin-like growth factor II receptor. > i6t> J. 8 r7j 1041-1047. 

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