Recycling of the dense-core vesicle membrane protein phogrin in Min6 beta-cells.
Phogrin (IA2-beta) is an integral membrane protein of dense-core vesicles in neuroendocrine cells. We have examined the recycling of endogenous phogrin following exocytosis in insulin secreting Min6 beta-cells by monitoring stimulus dependent-uptake of antibodies directed against the lumenal domain of the protein. While low levels of internalized phogrin accumulated in LAMP1-positive lysosomes, more than 35% of internalized phogrin recycled back to an insulin-positive compartment and could return to the cell surface during a second exocytic stimulation. The recycling phogrin transited a syntaxin 6-positive compartment but did not appear to go through the TGN38-positive trans Golgi network. The results suggest a model in which secretory membrane components can recycle from the endosomal system to immature secretory granules without interaction with the major portion of the TGN.
Vo
Yen P
YP
Department of Biological Sciences, University of Denver, Denver, CO 80208, USA.
Hutton
John C
JC
Angleson
Joseph K
JK
D000818:Animals; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D002645:Chickens; D004705:Endocytosis; D005089:Exocytosis; D006056:Golgi Apparatus / Q000378:metabolism*; D007091:Image Processing, Computer-Assisted; D007328:Insulin / Q000378:metabolism*; D007515:Islets of Langerhans / Q000378:metabolism*; D051907:Lysosomal Membrane Proteins; D008247:Lysosomes / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000737:chemistry / Q000378:metabolism; D008565:Membrane Proteins / Q000737:chemistry / Q000378:metabolism; D051379:Mice; D008856:Microscopy, Fluorescence; D017434:Protein Structure, Tertiary; D017027:Protein Tyrosine Phosphatases / Q000737:chemistry; D050765:Qa-SNARE Proteins; D011817:Rabbits; D054635:Receptor-Like Protein Tyrosine Phosphatases, Class 8; D013997:Time Factors; D021601:trans-Golgi Network / Q000378:metabolism; D052118:Lysosomal-Associated Membrane Protein 1
D007328:Insulin; D051907:Lysosomal Membrane Proteins; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D017027:Protein Tyrosine Phosphatases; D050765:Qa-SNARE Proteins; D054635:Receptor-Like Protein Tyrosine Phosphatases, Class 8; C489116:LAMP1 protein, human; D052118:Lysosomal-Associated Membrane Protein 1; C513047:Tgoln1 protein, mouse; C513046:Tgoln2 protein, mouse; C102889:PTPRN2 protein, human