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.
Department of Biological Sciences, University of Denver, Denver, CO 80208, USA.
Yen P
YP
Vo
John C
JC
Hutton
Joseph K
JK
Angleson
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