The Structure and Function of Monomeric Actin
Caroline Lussier
The Protein Data Bank is a free, updated archive and resource containing information about the structure of macromolecules including proteins and nucleic acids. This material allows users to better understand and compare the building blocks of life. More specifically, this database can help users to draw conclusions about how large molecule conformations help to determine the direction of drug development. The Protein Data Bank has a total of 114,080 deposited structures according to their Current Holdings Breakdown (1).
The PDB currently holds a data entry for a protein structure with the ID, 1NWK. This is a monomeric actin protein found in alpha skeletal muscle. Actin is significant …show more content…
This globular protein has four domains, each containing binding sites for ATP as well as an ion, usually calcium or magnesium, deep in the cleft between subunits 2 and 4. (2)
Figure 1. X-ray structure of rabbit muscle G-actin in complex with ATP and a Ca2+ ion. Included in this protein is a C-terminus and N-terminus with its four subunits displayed with different colors. The yellow ribbon represents the subdomain 4, blue represents subdomain 2, orange represents subdomain 3, and purple represents subdomain 1. ATP and Ca2+ also illustrated binding in the cleft between the yellow and blue domains. Image is taken from reference 2.
Polymerization of Monomeric Actin Because fibrous actin can vary in length, the successful crystallization of its structure has not been accomplished, leaving the understanding of its three-dimensional composition to electron micrographs. By using this technology, as well as x-ray studies of oriented gels of F-actin which result in low resolution models, researchers have been able to fit higher resolution G-actin models in order to better understand the orientation these fibers take. Applying this method, the resulting models illustrate a double-stranded helix of subunits. Within this helix, each domain remains in contact with four other subunits each with their nucleotide-binding clefts facing upwards. As result of this head-to-tail orientation, the fibrous molecule has a definite polarity with a (-) end toward which the nucleotide-binding site faces and a (+) end at the opposite side of the polymer
Caroline Lussier
The Protein Data Bank is a free, updated archive and resource containing information about the structure of macromolecules including proteins and nucleic acids. This material allows users to better understand and compare the building blocks of life. More specifically, this database can help users to draw conclusions about how large molecule conformations help to determine the direction of drug development. The Protein Data Bank has a total of 114,080 deposited structures according to their Current Holdings Breakdown (1).
The PDB currently holds a data entry for a protein structure with the ID, 1NWK. This is a monomeric actin protein found in alpha skeletal muscle. Actin is significant …show more content…
This globular protein has four domains, each containing binding sites for ATP as well as an ion, usually calcium or magnesium, deep in the cleft between subunits 2 and 4. (2)
Figure 1. X-ray structure of rabbit muscle G-actin in complex with ATP and a Ca2+ ion. Included in this protein is a C-terminus and N-terminus with its four subunits displayed with different colors. The yellow ribbon represents the subdomain 4, blue represents subdomain 2, orange represents subdomain 3, and purple represents subdomain 1. ATP and Ca2+ also illustrated binding in the cleft between the yellow and blue domains. Image is taken from reference 2.
Polymerization of Monomeric Actin Because fibrous actin can vary in length, the successful crystallization of its structure has not been accomplished, leaving the understanding of its three-dimensional composition to electron micrographs. By using this technology, as well as x-ray studies of oriented gels of F-actin which result in low resolution models, researchers have been able to fit higher resolution G-actin models in order to better understand the orientation these fibers take. Applying this method, the resulting models illustrate a double-stranded helix of subunits. Within this helix, each domain remains in contact with four other subunits each with their nucleotide-binding clefts facing upwards. As result of this head-to-tail orientation, the fibrous molecule has a definite polarity with a (-) end toward which the nucleotide-binding site faces and a (+) end at the opposite side of the polymer