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GTPases and their Regulation

GTPases and their Regulation

Guanine nucleotide-binding proteins (G-proteins), also known as GTPases, are a superfamily of proteins that regulate many cellular processes, such as cell signaling, vesicular transport, and the regulation of cell shape and motility. Mutation or dysfunction of these proteins can lead to disease. There are around 40,000 known G-proteins that can broadly be classified into two groups ‒ small G-proteins consisting of a single domain and large multi-domain G-proteins.
Large G-proteins, also known...

GTPases and their Regulation

GTPases and their Regulation

Guanine nucleotide-binding proteins (G-proteins), also known as GTPases, are a superfamily of proteins that regulate many cellular processes, such as cell signaling, vesicular transport, and the regulation of cell shape and motility. Mutation or dysfunction of these proteins can lead to disease. There are around 40,000 known G-proteins that can broadly be classified into two groups ‒ small G-proteins consisting of a single domain and large multi-domain G-proteins.
Large G-proteins, also known...

Allosteric Proteins-ATCase

Allosteric Proteins-ATCase

Binding sites linkages can regulate a protein's function. For example, enzyme activity is often regulated through a feedback mechanism where the end product of the biochemical process serves as an inhibitor.
Aspartate transcarbamoylase (ATCase) is a cytosolic enzyme that catalyzes the condensation of L-aspartate and carbamoyl phosphate to N-carbamoyl-L-aspartate. This reaction is the first step in pyrimidine biosynthesis. UTP and CTP, the end products of the pyrimidine synthesis pathway,...

Activation and Inactivation of G Proteins

Activation and Inactivation of G Proteins

Heterotrimeric G proteins are guanine nucleotide-binding proteins. As the name suggests, heterotrimeric G proteins are composed of three subunits: alpha, beta, and gamma. They remain GDP-bound or GTP-bound inside the cells and switch between inactive/active states. The Gα subunit possesses the nucleotide-binding pocket that binds guanine nucleotides and switches between GDP or GTP-bound states. In contrast, the Gꞵ and Gγ subunits are always bound together with high affinity and are together...

Regulated Protein Degradation

Regulated Protein Degradation

It is vital to regulate the activity of enzymatic as well as non-enzymatic proteins inside the cell. This can be achieved either through creating a balance between their rate of synthesis and degradation or regulating the intrinsic activity of the protein. Both these regulation mechanisms play an essential role in the normal functioning of cells.
Protein degradation plays two important roles in the cells. It helps to protect cells from misfolded or damaged proteins before they lead to a...

Regulated Protein Degradation

Regulated Protein Degradation

It is vital to regulate the activity of enzymatic as well as non-enzymatic proteins inside the cell. This can be achieved either through creating a balance between their rate of synthesis and degradation or regulating the intrinsic activity of the protein. Both these regulation mechanisms play an essential role in the normal functioning of cells.
Protein degradation plays two important roles in the cells. It helps to protect cells from misfolded or damaged proteins before they lead to a...

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Related Experiment Video

Updated: Jun 23, 2026

Imaging ATG9A, a Multi-Spanning Membrane Protein

Imaging ATG9A, a Multi-Spanning Membrane Protein

Published on: June 16, 2023

Evolution of Atg1 function and regulation.

Edmond Y Chan¹, Sharon A Tooze

¹Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, UK.

|May 5, 2009

Summary

This summary is machine-generated.

The serine/threonine kinase Atg1 regulates autophagy downstream of TOR. Evolution has expanded Atg1 protein functions and regulatory mechanisms in higher eukaryotes, impacting cell growth and survival.

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Area of Science:

Molecular Biology
Cell Biology
Evolutionary Biology

Background:

The serine/threonine kinase Atg1 is a key regulator of autophagy, acting downstream of the TOR pathway.
While Atg1's function in yeast involves a complex protein network and phosphorylation-dependent switch, its mammalian homologs (ULK1 and ULK2) show mechanistic differences.
Understanding these differences is crucial for comprehending autophagy regulation across species.

Purpose of the Study:

To review and synthesize current knowledge on Atg1 protein function in autophagy regulation.
To highlight evolutionary adaptations and functional diversification of Atg1 homologs in different organisms.
To propose a model for the expanded roles of Atg1 family members in higher eukaryotes.

Main Methods:

Comparative analysis of Atg1 homologs across species including yeast, C. elegans, D. melanogaster, and mammals.
Integration of existing research findings on Atg1 regulatory mechanisms and protein interactions.
Literature review and synthesis of data on Atg1 function in cellular processes.

Main Results:

Atg1 family members exhibit conserved roles in autophagy but possess distinct regulatory mechanisms and additional functions.
Mammalian ULK1 and ULK2 display mechanistic divergence from yeast Atg1 and from each other.
Gene family expansion in higher eukaryotes suggests increased functional diversity of Atg1 proteins.

Conclusions:

Atg1 proteins have evolved additional cellular functions beyond autophagy regulation.
Multiple gene family isoforms may operate within multifunctional complexes to achieve diverse roles.
Expanded Atg1 functions likely contribute to cell growth, differentiation, and survival in higher eukaryotes.