Biology subjects

Janetzko, J.

Publications and source records attributed to Janetzko, J..

2 recordsLinked to original sources

bioRxiv2021

Membrane phosphoinositides stabilize GPCR-arrestin complexes and offer temporal control of complex assembly and dynamics

Binding of arrestin to phosphorylated G protein-coupled receptors (GPCRs) is crucial for modulating signaling. Once internalized some GPCRs may complex with arrestin, while others interact transiently; this difference affects receptor signaling and recycling. Cell-based and in vitro biophysical assays reveal the role of membrane phosphoinositides (PIPs) in arrestin recruitment and GPCR-arrestin complex dynamics. We find that GPCRs broadly stratify into two groups, one requiring PIP-binding for arrestin recruitment and one that does not. Plasma membrane PIPs potentiate an active conformation of arrestin and stabilize GPCR-arrestin complexes by promoting a receptor core-engaged state of the complex. As allosteric modulators of GPCR-arrestin complex dynamics, membrane PIPs allow for additional conformational diversity beyond that imposed by GPCR phosphorylation alone. The dependance on membrane PIPs provides a mechanism for arrestin release from transiently associated GPCRs, allowing their rapid recycling, while explaining how stably associated GPCRs are able to engage G proteins at endosomes.

biochemistry↗

bioRxiv2020

Protein substrates engage the lumen of O-GlcNAc transferase's tetratricopeptide repeat domain in different ways

Glycosylation of nuclear and cytoplasmic proteins is an essential post-translational modification in mammals. O-GlcNAc transferase (OGT), the sole enzyme responsible for this modification, glycosylates over a thousand unique nuclear and cytoplasmic substrates. How OGT selects its substrates is a fundamental question that must be answered to understand OGTs unusual biology. OGT contains a long tetratricopeptide repeat (TPR) domain that has been implicated in substrate selection, but there is almost no information about how changes to this domain affect glycosylation of individual substrates. Here, we used proteome-wide glycosylation profiling and probed glycosylation of selected purified substrates to show that asparagine and aspartate ladders that extend the full length of OGTs TPR lumen control substrate glycosylation. We also found that substrates with glycosylation sites close to the C-terminus bypass lumenal binding. Our findings demonstrate that substrates can engage OGT in a variety of different ways for glycosylation.

biochemistry↗