Premium
GABA B receptor intracellular trafficking after internalization in Paramecium
Author(s) -
Ramoino Paola,
Usai Cesare,
Beltrame Francesco,
Fato Marco,
Gallus Lorenzo,
Tagliafierro Grazia,
Magrassi Raffaella,
Diaspro Alberto
Publication year - 2005
Publication title -
microscopy research and technique
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.536
H-Index - 118
eISSN - 1097-0029
pISSN - 1059-910X
DOI - 10.1002/jemt.20250
Subject(s) - endosome , internalization , microbiology and biotechnology , endocytosis , clathrin , golgi apparatus , vesicle , receptor , biology , lysosome , intracellular , biochemistry , membrane , endoplasmic reticulum , enzyme
The number of neurotransmitter receptors on the plasma membrane is regulated by the traffic of intracellular vesicles. Golgi‐derived vesicles provide newly synthesized receptors to the cell surface, whereas clathrin‐coated vesicles are the initial vehicles for sequestration of surface receptors, which are ultimately degraded or recycled. We have previously shown that GABA B receptors display a punctuate vesicular pattern dispersed on the cell surface and throughout the cytoplasm and are internalized via clathrin‐dependent and ‐independent endocytosis. Here we have studied constitutive GABA B receptor trafficking after internalization in Paramecium primaurelia by confocal laser scanning microscopy and multiple immunofluorescence analysis. After internalization, receptors are targeted to the early endosomes characterized by the molecular markers EEA1 and rab5. Some of these receptors, destined for recycling back to the plasma membrane, traffic from the early endosomes to the endosomal recycling compartment that is characterized by the presence of rab4‐immunoreactivity (IR). Receptors that are destined for degradation exit the endosomal pathway at the early endosomes and traffic to the late endosome–lysosome pathway. In fact, some of the GABA B ‐positive compartments were identified as lysosomal structures by double staining with the lysosomal marker LAMP‐1. GABA B vesicle structures also colocalize with TGN38‐IR and rab11‐IR. TGN38 and rab11 are proteins found in association with post‐Golgi and recycling endosomes, respectively. Microsc. Res. Tech. 68:290–295, 2005. © 2005 Wiley‐Liss, Inc.