Chick cytoplasmic actin and muscle actin have different structural genes

Area of Science:

• Molecular Biology
• Developmental Biology
• Biochemistry

Background:

• Actins are essential cytoskeletal proteins with known isoforms.
• Differences in electrophoretic mobility between brain and muscle actin suggest potential genetic or post-translational variations.

Purpose of the Study:

• To investigate whether embryonic chick brain and muscle actins originate from distinct structural genes or result from post-translational modifications.
• To explore the role of messenger RNA in the synthesis of different actin types.
• To understand actin gene regulation during muscle cell differentiation.

Main Methods:

• Cell-free protein synthesis using wheat germ extracts and messenger RNA from embryonic chick brain and muscle.
• Identification of synthesized actins via conversion to fibrous form and two-dimensional chromatographic analysis of tryptic peptides.
• Electrophoresis in gels containing urea and sodium dodecyl sulfate to compare actin mobility.

Main Results:

• Electrophoretic mobility differences between brain and muscle actin persisted in cell-free synthesized proteins.
• These differences were not attributable to post-translational modifications.
• Messenger RNA from embryonic thigh muscle directed the synthesis of both brain- and muscle-type actins.

Conclusions:

• Brain and muscle actins are encoded by different messenger RNAs, originating from distinct structural genes.
• Muscle cell differentiation appears to involve the coordinated regulation of at least two different actin genes.