Related Experiment Video
Updated: Aug 11, 2026
08:57
Aip1p Dynamics Are Altered by the R256H Mutation in Actin
Published on: July 30, 2014
Actin nascent chains are substrates for cyclic AMP-dependent phosphorylation in vivo
Summary
Cyclic AMP (cAMP) regulates nonmuscle actin phosphorylation in S49 mouse lymphoma cells. Nascent actin is phosphorylated, suggesting a role for cAMP in actin dynamics and gene regulation.
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- Actin is a crucial cytoskeletal protein involved in various cellular processes.
- Cyclic AMP (cAMP) is a key second messenger regulating numerous cellular functions.
- Post-translational modifications of actin can influence its function and dynamics.
Purpose of the Study:
- To identify proteins regulated by cyclic AMP (cAMP) in S49 mouse lymphoma cells.
- To investigate the role of cAMP in the post-translational modification of actin.
- To explore the relationship between different actin isoforms and their phosphorylation status.
Main Methods:
- Two-dimensional gel electrophoresis of [35S]methionine-labeled S49 cell extracts.
- Affinity purification and peptide mapping to identify proteins.
- Cyclic AMP-dependent labeling with [32P]phosphate to detect phosphorylation.
- Analysis of actin microheterogeneity using staphylococcal protease digestion.
Main Results:
- A nonmuscle actin isoform was identified as being regulated by cAMP.
- This actin species undergoes cAMP-dependent phosphorylation on serine.
- Phosphorylation is specific to nascent actin, indicating a role for protein synthesis.
- Microheterogeneity observed in actin isoforms (beta, gamma, delta/epsilon) is also present in phosphorylated actin.
Conclusions:
- Cyclic AMP signaling directly influences the phosphorylation of nascent nonmuscle actin.
- Actin phosphorylation may be a mechanism for regulating actin dynamics or cellular responses to cAMP.
- The observed microheterogeneity suggests that different actin forms arise from a limited number of gene products and are subject to similar regulatory modifications.
Related Concept Videos
01:24Intracellular Signaling Cascades
Once a ligand binds to a receptor, the signal is transmitted through the membrane and into the cytoplasm. The continuation of a signal in this manner is called signal transduction. Signal transduction only occurs with cell-surface receptors, which cannot interact with most components of the cell, such as DNA. Only internal receptors can interact directly with DNA in the nucleus to initiate protein synthesis. When a ligand binds to its receptor, conformational changes occur that affect the...
01:26Introduction to Actin
Actin is a highly conserved cytoskeletal protein found abundantly in eukaryotic cells. It constitutes 10% weight of the total cellular protein in muscle cells, while in non-muscle cells, it is lower and makes up around 1–5 percent of the total cell protein. Actin found in the unicellular amoebae and complex multicellular animals is around 80% similar, demonstrating their conservation over a billion years of evolution. Actin coding genes are conserved within species and across different species.
01:42Actin Polymerization
Actin polymerization occurs through the head-to-tail association of binding sites on monomeric actin or G-actin to form filamentous or F-actin. The polymerization can be divided into three phases ̶ nucleation, elongation, and steady-state phase.
The nucleation phase involves forming a stable nucleus consisting of three actin monomers to form a new actin filament. Actin-binding proteins such as formins and Arp2/3 complex help filament growth post-nucleation. The Formins form straight actin...
The nucleation phase involves forming a stable nucleus consisting of three actin monomers to form a new actin filament. Actin-binding proteins such as formins and Arp2/3 complex help filament growth post-nucleation. The Formins form straight actin...
01:14Generation of Straight or Branched Actin Filaments
The straight or branched structure formation of actin filaments is controlled by nucleating proteins such as the formins and Arp2/3 complex. Formin-mediated assembly results in straight filaments, whereas Arp2/3 protein complex-mediated assembly results in branched actin filaments.
Arp2/3 Complex
Arp2/3 complex is a seven-subunit complex consisting of two proteins similar to actin- Arp2 and Arp3, and five other subunits that help keep Arp2 and Arp3 inactive. When required, the complex is...
Arp2/3 Complex
Arp2/3 complex is a seven-subunit complex consisting of two proteins similar to actin- Arp2 and Arp3, and five other subunits that help keep Arp2 and Arp3 inactive. When required, the complex is...
01:48ATP Synthase: Mechanism
In animals, the mitochondrial F1F0 ATP synthase is the key protein that synthesizes ATP molecules through a complex catalytic mechanism. While the nuclear genome encodes the majority of ATP synthase subunits, the mitochondrial genome encodes some of the enzyme's most critical components. The formation of this multi-subunit enzyme is a complex multi-step process regulated at the level of transcription, translation, and assembly. Defects in one or more of these steps can result in decreased ATP...
01:25cAMP-dependent Protein Kinase Pathways
Cyclic Adenosine Monophosphate (cAMP) is an essential second messenger that activates protein kinase A (PKA) and regulates various biological processes. A single epinephrine molecule binds to GPCR and activates several heterotrimeric G proteins, each stimulating multiple adenylyl cyclase, amplifying the signal, and synthesizing large numbers of cAMP molecules. Small changes in cAMP concentration affect PKA activity. The binding of four cAMP molecules induces a conformational change in PKA,...