Neuroproteomics is the study of the protein complexes and species that make up the nervous system. These proteins interact to make the neurons connect in such a way to create the intricacies that nervous system is known for. Neuroproteomics is a complex field that has a long way to go in terms of profiling the entire neuronal proteome. It is a relatively recent field that has many applications in therapy and science. So far, only small subsets of the neuronal proteome have been mapped, and then only when applied to the proteins involved in the synapse.
History
Origins The word proteomics was first used in 1994 by Marc Wilkins as the study of “the protein equivalent of a genome”. It is defined as all of the proteins expressed in a biological system under specific physiologic conditions at a certain point in time. It can change with any biochemical alteration, and so it can only be defined under certain conditions. Neuroproteomics is a subset of this field dealing with the complexities and multi-system origin of neurological disease. Neurological function is based on the interactions of many proteins of different origin, and so requires a systematic study of subsystems within its proteomic structure.
Modern times Neuroproteomics has the difficult task of defining on a molecular level the pathways of consciousness, senses, and self. Neurological disorders are unique in that they do not always exhibit outward symptoms. Defining the disorders becomes difficult and so neuroproteomics is a step in the right direction of identifying bio-markers that can be used to detect diseases. Not only does the field have to map out the different proteins possible from the genome, but there are many modifications that happen after transcription that affect function as well. Because neurons are such dynamic structures, changing with every action potential that travels through them, neuroproteomics offers the most potential for mapping out the molecular template of their function. Genomics offers a static roadmap of the cell, while proteomics can offer a glimpse into structures smaller than the cell because of its specific nature to each moment in time.
Mechanisms of Use
Protein Separation In order for neuroproteomics to function correctly, proteins must be separated in terms of the proteome from which they came. For example, one set might be under normal conditions, while another might be under diseased conditions. Proteins are commonly separated using two-dimensional polyacrylamide gel electrophoresis (2D PAGE). For this technique, proteins are run across an immobile gel with a pH gradient until they stop at the point where their net charge is neutral. After separating by charge in one direction, sodium dodecyl sulfate is run in the other direction to separate the proteins by size. A two-dimensional map is created using this technique that can be used to match additional proteins later. One can usually match the function of a protein by identifying in an 2D PAGE in simple proteomics because many intracellular somatic pathways are known. In neuroproteomics, however, many proteins combine to give an end result that may be neurological disease or breakdown. It is necessary then to study each protein individually and find a correlation between the different proteins to determine the cause of a neurological disease. New techniques are being developed that can identify proteins once they are separated out using 2D PAGE.
Protein Identification Protein separate techniques, such as 2D PAGE, are limited in that they cannot handle very high or low molecular weight protein species. Alternative methods have been developed to deal with such cases. These include liquid chromatography mass spectrometry along with sodium dodecyl sulfate polyacrylamide gel electrophoresis, or liquid chromatography mass spectrometry run in multiple dimensions. Compared to simple 2D page, liquid chromatography mass spectrometry can handle a larger range of protein species size, but it is limited in the amount of protein sample it handle at once. Liquid chromatography mass spectrometry is also limited in its lack of a reference map from which to work with. Complex algorithms are usually used to analyze the fringe results that occur after a procedure is run. The unknown portions of the protein species are usually not analyzed in favor of familiar proteomes, however. This fact reveals a fault with current technology; new techniques are needed to increase both the specificity and scope of proteome mapping.
Applications
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