Send to

Choose Destination
Traffic. 2002 Oct;3(10):752-61.

AP-1A and AP-3A lysosomal sorting functions.

Author information

Zentrum für Biochemie and Molekulare Zellbiologie, Department of Biochemie II, Universität Göttingen, Heinrich-Düker-Weg 12, D-37073 Göttingen, Germany.


Heterotetrameric adaptor-protein complexes AP-1A and AP-3A mediate protein sorting in post-Golgi vesicular transport. AP-1A and AP-3A have been localized to the trans-Golgi network, indicating a function in protein sorting at this compartment. AP-3A appears to mediate trans-Golgi network-to-lysosome and also endosome-to-lysosome protein sorting. AP-1A is thought to be required for both trans-Golgi network-to-endosome transport and endosome-to-trans-Golgi network transport. However, the recent discovery of a role for monomeric GGA (Golgi localized gamma-ear containing, ARF binding protein) adaptor proteins in trans-Golgi network to endosome protein transport has brought into question the long-discussed trans-Golgi network-to-endosome sorting function of AP-1A. Murine cytomegalovirus gp48 contains an unusual di-leucine-based lysosome sorting signal motif and mediates lysosomal sorting of gp48/major histocompatibility complex class I receptor complexes, preventing exposure of major histocompatibility complex class I at the plasma membrane. We analyzed lysosomal sorting of gp48/major histocompatibility complex class I receptor complexes in cell lines deficient for AP-1A, AP-3A and both, to determine their sorting functions. We find that AP1-A and AP3-A mediate distinct and sequential steps in the lysosomal sorting. Both sorting functions are required to prevent MHC class I exposure at the plasma membrane at steady-state.

[Indexed for MEDLINE]
Free full text

Supplemental Content

Full text links

Icon for Wiley
Loading ...
Support Center