Clathrin protein assembly forms two basket sizes. A 110,000-dalton protein is essential for smaller 150S baskets, while its absence yields larger 300S baskets.
Area of Science:
Cell biology
Protein biochemistry
Background:
Clathrin is a protein that self-assembles into coat structures, forming baskets similar to those on coated vesicles.
Clathrin polymerization can result in different basket sizes, influenced by preparation purity and other factors.
Purpose of the Study:
To investigate the factors influencing clathrin basket size formation.
To identify proteins involved in the assembly of specific clathrin structures.
Main Methods:
Lysine-Sepharose chromatography was used to separate proteins from clathrin preparations.
Clathrin polymerization was studied in the presence and absence of a specific protein and in the presence of divalent cations (Ca2+, Mg2+).
Main Results:
A 110,000-dalton protein was isolated from clathrin.
This 110,000-dalton protein is required for the formation of 150S clathrin baskets.
In the absence of the 110,000-dalton protein, clathrin polymerizes into larger 300S baskets.
Divalent cations (Ca2+ or Mg2+) stimulate the formation of 300S baskets when the 110,000-dalton protein is present.
Conclusions:
The assembly of clathrin into distinct basket sizes is regulated by accessory proteins, such as the 110,000-dalton protein.
The 110,000-dalton protein plays a critical role in directing clathrin polymerization towards the formation of 150S structures.
Environmental factors like divalent cations can modulate clathrin assembly pathways.
