Microtubule Associated Protein
Microtubule-associated proteins (MAPs) bind to the microtubules in the cell skeleton or to adjacent membranes and thus influence numerous processes inside them.
function
MAPs are generally all proteins that interact directly with the microtubules of a cell in various ways . They regulate their growth behavior and link them together, so they play an important role as the basic proteins of the neuronal cytoskeleton. Due to their ability to bind, they can stabilize and destabilize microtubules and, as dynamic molecules, are subject to constant lengthening and shortening phases. With the help of pontics that form the MAPs, they can counteract the destabilization and thus the shortening. If this is not desired, the MAP2 kinase phosphorylizes the MAPs and lowers their affinity. A regulatory path arises that controls the remodeling of the microtubule network through extracellular signals. MAPs also determine the cellular location of the microtubules and interactions with other organelles . They also build higher-level structures from several microtubules, including star-shaped bundles or asters. In cell division they play a stabilizing role in the microtubules.
Protein types
Since their discovery, more and more MAP subgroups have been found and described, and overlaps with proteins that had already been discovered were not always immediately apparent.
- Motor proteins
- Most frequently, MAPs are represented as motor proteins dynein , myosin and kinesin ; these are responsible for the essential supply of biological loads in intracellular transport. They transport the material required for protein biosynthesis directionally on cytoskeletal structures along the microtubules, as protein biosynthesis cannot take place in the axon itself. Kinesins continue to play a central role in the structure and function of the mitotic spindle and are primarily responsible for transporting cell components to the microtubule plus end.
- Structural MAPs
- MAP2 / Tau proteins belong to the structural MAPs and influence numerous processes through microtubule bonds, but do not have any enzymatic activity themselves. Adapter proteins, which ensure the activity of other MAPs, and + TIPs are also structural MAPs and are considered to be well researched.
- + TIPs
- + TIPs influence cellular structures in the microtubules. They link growing microtubule ends, to which they exclusively bind, with remaining organelles in the cell.
- Actin-microtubule connecting proteins
- Actin-microtubule connecting proteins can bind to both microtubules and actin . They are involved in many cellular processes, for example in wound healing or neuronal development. Well-researched representatives are the spectral posters.
Mutations in MAPs lead to severe damage in the organism. Some neurodegenerative diseases occur when there are errors in the MAPs, for example tauopathies can result from deposits of tau proteins in the brain , including Alzheimer's disease .
Individual evidence
- ↑ a b c d e Julia Arens: The role of microtubule-regulating proteins during neuronal differentiation , 2012, Technical University Dortmund, Max Planck Institute for Molecular Physiology.
- ↑ a b zhb.uni-luebeck.de: Immunohistochemical studies of microtubule-associated protein 2 (MAP2) in death from asphyxiation, last accessed January 22, 2016
- ↑ a b mpg.de: Cytoskeleton: Architecture and Movement of the Cell, last accessed January 22, 2016