[Protein synthesizing structures and protein synthesis in mouse lymphocytes]

Area of Science:

• Molecular Biology
• Cell Biology
• Biochemistry

Context:

• Investigates cytoplasmic messenger ribonucleoprotein (mRNP) particles in spleen lymphocytes.
• Examines the kinetics of amino acid incorporation into these particles at early time points (5-60 seconds).
• Characterizes mRNP particle properties including sedimentation coefficients and buoyant density.

Purpose:

• To elucidate the early stages of protein synthesis and polysome assembly in lymphocytes.
• To determine the temporal sequence of amino acid labeling in different mRNP fractions.
• To understand the role of informosomes in initiating translation.

Summary:

• Short-term amino acid labeling revealed sequential incorporation into small (≤80S) and then larger (80-120S and polysomal) mRNP particles.
• Distinct buoyant densities were observed for different particle sizes, indicating compositional differences.
• Data suggest translation initiates on informosome-ribosome complexes and proceeds as these complexes mature into polysomes.

Impact:

• Provides insights into the dynamic process of translation initiation and elongation in lymphocytes.
• Establishes a method using pulse labeling to estimate polypeptide chain synthesis time.
• Contributes to understanding gene expression regulation at the post-transcriptional level.