Fluctuations, Correlations and the Estimation of Concentrations inside Cells

Area of Science:

• Cellular and Molecular Biophysics
• Biochemical Kinetics
• Systems Biology

Background:

• Cellular information transmission relies on ligand-receptor interactions.
• Accurate signaling persists despite fluctuations in molecular concentrations.
• Understanding these fluctuations is key to cellular function.

Purpose of the Study:

• To analyze ligand number and site occupancy fluctuations beyond asymptotic decay.
• To investigate the timescales of bound molecule number decay.
• To correlate fluctuation dynamics with cellular activities like transcription and enzyme kinetics.

Main Methods:

• Mathematical modeling of ligand diffusion and reaction kinetics.
• Analysis of fluctuations in bound molecule numbers and site occupancy.
• Examination of transient and asymptotic decay behaviors.

Main Results:

• Fluctuations in bound molecules for immobile sites decay rapidly before reaching asymptotic behavior.
• The initial decay exhibits one or two timescales, dependent on free ligand concentration.
• This dynamic behavior explains the coexistence of high instantaneous transcriptional activity with low mRNA noise.

Conclusions:

• Cellular signaling accuracy is maintained by rapid decay of binding fluctuations.
• Characteristic timescales in fluctuation decay provide insights into enzyme activity regulation.
• The study offers a mechanistic explanation for observed cellular noise levels and activity dynamics.