Protein complex

Protein complexes are distinct from multidomain enzymes, in which multiple catalytic domains are found in a single polypeptide chain.

The cell is seen to be composed of modular supramolecular complexes, each of which performs an independent, discrete biological function.

[2] Through proximity, the speed and selectivity of binding interactions between enzymatic complex and substrates can be vastly improved, leading to higher cellular efficiency.

In stable complexes, large hydrophobic interfaces between proteins typically bury surface areas larger than 2500 square Ås.

Factors include: Many protein complexes are well understood, particularly in the model organism Saccharomyces cerevisiae (yeast).

[citation needed] In 2021, researchers used deep learning software RoseTTAFold along with AlphaFold to solve the structures of 712 eukaryote complexes.

[5] Note that there is no clear distinction between obligate and non-obligate interaction, rather there exist a continuum between them which depends on various conditions e.g. pH, protein concentration etc.

[20] Homooligomers are responsible for the diversity and specificity of many pathways, may mediate and regulate gene expression, activity of enzymes, ion channels, receptors, and cell adhesion processes.

The voltage-gated potassium channels in the plasma membrane of a neuron are heteromultimeric proteins composed of four of forty known alpha subunits.

When multiple copies of a polypeptide encoded by a gene form a complex, this protein structure is referred to as a multimer.

An analysis of the results from such studies led to the conclusion that intragenic complementation, in general, arises from the interaction of differently defective polypeptide monomers to form a multimer.

[25] The molecular structure of protein complexes can be determined by experimental techniques such as X-ray crystallography, Single particle analysis or nuclear magnetic resonance.

Recently, Raicu and coworkers developed a method to determine the quaternary structure of protein complexes in living cells.

This method is based on the determination of pixel-level Förster resonance energy transfer (FRET) efficiency in conjunction with spectrally resolved two-photon microscope.

[31] The opposite phenomenon is observed in heteromultimeric complexes, where gene fusion occurs in a manner that preserves the original assembly pathway.