Characterization of the Extra-large G Protein α-Subunit XLαs
By Amalia H. Pasolli, M. Klemke, R. Kehlenbach, Yanzhuang Wang, W. Huttner. Journal of Biological Chemistry, 2000
95 citations recorded by the source corpus.
Our group previously described a new type of G protein, the 78-kDa XLαs (extra large αs) (Kehlenbach, R. H., Matthey, J., and Huttner, W. B. (1994) Nature 372, 804–809 and (1995) Nature375, 253). Upon subcellular fractionation, XLαs labeled by ADP-ribosylation with cholera toxin was previously mainly detected in the bottom fractions of a velocity sucrose gradient that contained trans-Golgi network and was differentially distributed to Gαs, which also peaked in the top fractions containing plasma membrane. Here, we investigate, using a new antibody specific for the XL domain, the tissue distribution and subcellular localization of XLαs and novel splice variants referred to as XLN1. Upon immunoblotting and immunofluorescence analysis of various adult rat tissues, XLαs and XLN1 were found to be enriched in neuroendocrine tissues, with a particularly high level of expression in the pituitary. By both immunofluorescence and immunogold electron microscopy, endogenous as well as transfected XLαs and XLN1 were found to be predominantly associated with the plasma membrane, with only little immunoreactivity on internal, perinuclear membranes. Upon subcellular fractionation, immunoreactive XLαs behaved similarly to Gαs but was differentially distributed to ADP-ribosylated XLαs. Moreover, the bottom fractions of the velocity sucrose gradient were found to contain not only trans-Golgi network membranes but also certain subdomains of the plasma membrane, which reconciles the present with the previous observations. To further investigate the molecular basis of the association of XLαs with the plasma membrane, chimeric proteins consisting of the XL domain or portions thereof fused to green fluorescent protein were analyzed by fluorescence and subcellular fractionation. In both neuroendocrine and non-neuroendocrine cells, a fusion protein containing the entire XL domain, in contrast to one containing only the proline-rich and cysteine-rich regions, was exclusively localized at the plasma membrane. We conclude that the physiological role of XLαs is at the plasma membrane, where it presumably is involved in signal transduction processes characteristic of neuroendocrine cells.
Subfields: Cell Biology, Molecular Biology
View Paper: https://www.semanticscholar.org/paper/218cfad63964e1922034cb5a4ad46ac51946d9e7
How researchers see this paper
The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.
In Cell Biology
In Molecular Biology
Citations in the corpus
- Receptor-Mediated Adenylyl Cyclase Activation Through XLαs, the Extra-Large Variant of the Stimulatory G Protein α-Subunit (2002, background): “However, a more recent report has refuted these previous findings by demonstrating that this protein is primarily localized to the plasma membrane (9).”