Cycling of early Golgi proteins via the cell surface and endosomes upon lumenal pH disruption.
The cis-Golgi protein GPP130 reversibly redistributes to endosomes upon pH disruption, but the identity of the endosomes and the involved cycling route are unknown. It is also unknown whether any other early Golgi proteins participate in this pathway. Here, we analyze GPP130 and the structurally related Golgi protein GP73. Unlike the TGN marker TGN38/46, GPP130 and GP73 colocalized in the early Golgi and redistributed to the ER after brefeldin A treatment. Nevertheless, after pH disruption by monensin, GPP130 and GP73 redistributed to endosomes containing redistributed TGN38/46, but not other endosomal markers. In common with TGN38/46, the redistribution involved transient appearance on the plasma membrane, and upon monensin washout, the proteins moved back to the Golgi along a microtubule- and PI3 kinase-independent route. Although GP73 did not associate with GPP130, its steady-state Golgi targeting was also mediated by a lumenal predicted coiled-coil stem domain. These findings indicate that at least two early Golgi proteins, each containing stem domain Golgi targeting determinants, cycle to the cell surface and back along the late endosome independent TGN38/46 pathway.
Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA 15213, USA.
Sapna
S
Puri
Collin
C
Bachert
Claus J
CJ
Fimmel
Adam D
AD
Linstedt
D000818:Animals; D001483:Base Sequence; D020126:Brefeldin A / Q000494:pharmacology; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D017931:DNA Primers; D011992:Endosomes / Q000378:metabolism*; D006023:Glycoproteins; D006056:Golgi Apparatus / Q000187:drug effects / Q000378:metabolism*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008562:Membrane Glycoproteins / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism*; D010750:Phosphoproteins / Q000378:metabolism*; D021381:Protein Transport; D033921:Vesicular Transport Proteins
C081876:CKAP4 protein, human; D017931:DNA Primers; C107340:GOLIM4 protein, human; C410824:GOLM1 protein, human; D006023:Glycoproteins; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D010750:Phosphoproteins; C072237:TGOLN2 protein, human; D033921:Vesicular Transport Proteins; D020126:Brefeldin A