The hinge region of the lutropin receptor mediates different activation mechanisms: CG induces trans- and LH only cis-initialization

AbstractThiol-based redox switches evolved as efficient post-translational regulatory mechanisms that enable individual proteins to rapidly respond to sudden environmental changes. While some protein functions need to be switched off to save resources and avoid potentially error-prone processes, protective functions become essential and need to be switched on. In this review, we focus on thiol-based activation mechanisms of stress-sensing chaperones. Upon stress exposure, these chaperones convert into high affinity binding platforms for unfolding proteins and protect cells against the accumulation of potentially toxic protein aggregates. Their chaperone activity is independent of ATP, a feature that becomes especially important under oxidative stress conditions, where cellular ATP levels drop and canonical ATP-dependent chaperones no longer operate. Vice versa, reductive inactivation and substrate release require the restoration of ATP levels, which ensures refolding of client proteins by ATP-dependent foldases. We will give an overview over the different strategies that cells evolved to rapidly increase the pool of ATP-independent chaperones upon oxidative stress and provide mechanistic insights into how stress conditions are used to convert abundant cellular proteins into ATP-independent holding chaperones.

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O-glycosylation in hinge region of mouse immunoglobulin G2b.

Journal of Biological Chemistry ◽

10.1016/s0021-9258(17)32722-9 ◽

1994 ◽

Vol 269 (16) ◽

pp. 12345-12350 ◽

Cited By ~ 2

Author(s):

H. Kim ◽

Y. Yamaguchi ◽

K. Masuda ◽

C. Matsunaga ◽

K. Yamamoto ◽

...

Keyword(s):

Hinge Region ◽

Mouse Immunoglobulin

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Structure–function analysis of oncogenic EGFR Kinase Domain Duplication reveals insights into activation and a potential approach for therapeutic targeting

Nature Communications ◽

10.1038/s41467-021-21613-6 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Zhenfang Du ◽

Benjamin P. Brown ◽

Soyeon Kim ◽

Donna Ferguson ◽

Dean C. Pavlick ◽

...

Keyword(s):

Tandem Duplication ◽

Function Analysis ◽

Treatment Strategies ◽

Kinase Domain ◽

Time Resolved ◽

Egfr Activation ◽

Domain Duplication ◽

Activation Mechanisms ◽

Potential Therapeutic Intervention ◽

Egfr Kinase

AbstractMechanistic understanding of oncogenic variants facilitates the development and optimization of treatment strategies. We recently identified in-frame, tandem duplication of EGFR exons 18 - 25, which causes EGFR Kinase Domain Duplication (EGFR-KDD). Here, we characterize the prevalence of ERBB family KDDs across multiple human cancers and evaluate the functional biochemistry of EGFR-KDD as it relates to pathogenesis and potential therapeutic intervention. We provide computational and experimental evidence that EGFR-KDD functions by forming asymmetric EGF-independent intra-molecular and EGF-dependent inter-molecular dimers. Time-resolved fluorescence microscopy and co-immunoprecipitation reveals EGFR-KDD can form ligand-dependent inter-molecular homo- and hetero-dimers/multimers. Furthermore, we show that inhibition of EGFR-KDD activity is maximally achieved by blocking both intra- and inter-molecular dimerization. Collectively, our findings define a previously unrecognized model of EGFR dimerization, providing important insights for the understanding of EGFR activation mechanisms and informing personalized treatment of patients with tumors harboring EGFR-KDD. Finally, we establish ERBB KDDs as recurrent oncogenic events in multiple cancers.

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Primary structure of the "hinge" region of human IgG3. Probable quadruplication of a 15-amino acid residue basic unit.

Journal of Biological Chemistry ◽

10.1016/s0021-9258(19)75181-3 ◽

1977 ◽

Vol 252 (3) ◽

pp. 883-889

Author(s):

T E Michaelsen ◽

B Frangione ◽

E C Franklin

Keyword(s):

Amino Acid ◽

Amino Acid Residue ◽

Primary Structure ◽

Hinge Region ◽

Basic Unit

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Species-Specific Regulation of TRPM2 by PI(4,5)P2 via the Membrane Interfacial Cavity

International Journal of Molecular Sciences ◽

10.3390/ijms22094637 ◽

2021 ◽

Vol 22 (9) ◽

pp. 4637

Author(s):

Daniel Barth ◽

Andreas Lückhoff ◽

Frank J. P. Kühn

Keyword(s):

Amino Acid Residues ◽

Hek 293 ◽

Complete Inactivation ◽

293 Cells ◽

Activation Mechanisms ◽

Specific Regulation ◽

Species Specific ◽

Inside Out ◽

Positively Charged

The human apoptosis channel TRPM2 is stimulated by intracellular ADR-ribose and calcium. Recent studies show pronounced species-specific activation mechanisms. Our aim was to analyse the functional effect of phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2), commonly referred to as PIP2, on different TRPM2 orthologues. Moreover, we wished to identify the interaction site between TRPM2 and PIP2. We demonstrate a crucial role of PIP2, in the activation of TRPM2 orthologues of man, zebrafish, and sea anemone. Utilizing inside-out patch clamp recordings of HEK-293 cells transfected with TRPM2, differential effects of PIP2 that were dependent on the species variant became apparent. While depletion of PIP2 via polylysine uniformly caused complete inactivation of TRPM2, restoration of channel activity by artificial PIP2 differed widely. Human TRPM2 was the least sensitive species variant, making it the most susceptible one for regulation by changes in intramembranous PIP2 content. Furthermore, mutations of highly conserved positively charged amino acid residues in the membrane interfacial cavity reduced the PIP2 sensitivity in all three TRPM2 orthologues to varying degrees. We conclude that the membrane interfacial cavity acts as a uniform PIP2 binding site of TRPM2, facilitating channel activation in the presence of ADPR and Ca2+ in a species-specific manner.

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