What is cellular communication definition. What is mobile communication? Reasons for the rise in communication prices

Glycosylated extracellular molecule that recognizes and fixes a molecule, transmembrane, membrane-anchored, intracellular, responsible for biochemical events. Each informative molecule corresponds to a receiver, but an informative molecule can have multiple receivers. We define receiver families. This is due to three types of responses, allowing us to distinguish three main types of receivers.

Ion receivers

Ion channel receivers that reduce the signal itself; enzyme receptors that transduce the signal itself; receptors in combination with various effectors, requiring the intervention of other proteins for signal transmission. These are hetero-oligomeric transmembrane proteins with a region of hydrophobic anchorage in the membrane, this region forms a central pore, separated by subunits, where ions pass when the receptor is activated, open. ion channels - dual function of recognizing signals and effectors. Informative molecules of ion channel receptors are neurotransmitters, and therefore their receptors are localized in nerve networks: synapses and motor plates.

Activating receptor: nicotinic acetylcholine receptor

If it is cations that pass through, depolarization will occur and therefore activation. If anions pass through, polarization and therefore inhibition will occur. It is localized on the motor plates of the neuromuscular junction. Its agonist is nicotine, its antagonist is curare.

These are α subunits that contain acetylcholine binding sites. The basic structure is similar to that of the nicotinic receptor: five protein subunits, each of which has four transmembrane segments, but unlike nicotinic receptors it has seven types of subunits. possible units: α, β, γ, δ, π, ρ, ε, where there is a very large variety of receivers. These transmembrane proteins exist in the form of monomers, dimers and tetramers. They have the dual function of signal and effector recognition.

Receptor tyrosine kinase activity

According to the enzymatic activity of their cellular region, three families are distinguished. Tyrosine kinase activity receptors, serine-threonine kinase activity receptors, guanylate cyclase activity receptors. Two examples are known: the receptor for several growth factors and the insulin receptor. These receptors do not have a dual function; they do not lead to an electrophysiological response. The insulin receptor is a tetratramine compound. of two αβ-linked heterodimers linked by two disulfide bridges, with two different subunits α and β themselves linked to a disulfide bridge.

The two heterodimers are associated with α subunits, extramembrane subunits that allow insulin binding. The transmembrane β subunit contains a domain with tyrosine kinase activity in the intracellular domain responsible for message transduction. When insulin binds to the α subunits, a spatial conformational change occurs that activates the kinase domain of the two β subunits. The β-subunit tyrosines are then phosphorylated by the opposing β-subunit, and the phosphoryl receptor then recruits the receptor substrate protein to the membrane to phosphorylate it in turn and thus trigger a cascade of events. biochemical substances leading to an adaptive response.

Receptors with serine-threonine kinase activity

This is a quick response after the transcript. In addition, tetramine is formed from four transmembrane subunits, each of which has serine-threonine kinase activity. The same phenomenon of autophosphorylation of intracellular regions is observed, followed by phosphorylation of protein transcription factors.

Receptors with guanylate cyclase activity

Receptors with guanylate cyclase activity are receptors for natriuretic peptides. It is a homodimeric transmembrane.

Receivers connected to individual effectors

They correspond to indirect receptor-enzyme bonds and are also called serpentine receptors. These numerous receptors allow information to be transmitted. It consists of three membrane-anchored subunits α, β, γ, α and β. It then activates the enzymatic effector protein. Adenylate cyclase is an integral membrane protein with 12 transmembrane segments. Enzymatic activity is carried out on two imported intracellular domains. It activates protein kinase A, which is also a serine-threonine kinase.

Phospholipase C is attached to the inner surface of the membrane. It allows hydrolysis of the phosphodiester bond of phosphatidylinositol 4, 5-bisphosphate, producing two second messengers: inositol 1, 4, 5-trisphosphate, released in the cytosol, and diacylglycerol, which remains attached to the membrane.

Tyrosine kinase-related receptors

The receptor is a monomer bound intracellularly to an enzymatic protein with tyrosine kinase activity. When the messenger molecule binds, the receptor becomes dimmed and then allows cross-phosphorylation of intracellular domains. The phosphorylated receptor is then recruited to the membrane of protein substrates to be phosphorylated in turn by tyrosine kinase. These proteins are transcription factors.

They interfere with the modulation of gene transcription. They are soluble proteins activated by the binding of an information molecule. They are usually localized in the nucleus, with the exception of the glucocorticoid receptor, which is located in the cytosol. They have three main areas.

Inter- and intracellular communication. It is estimated that 2 billion years passed between the appearance of the first single-celled organisms and the subsequent establishment of multicellular organisms and that this time was greatly facilitated by the development of communication mechanisms that allow the coordination of the actions of individual human cells. Cell-to-cell communication occurs both through direct cellular interaction and through signaling that is produced in a part of the body and influences the behavior of target cells in other areas.

Individual cells in a higher organism are so dependent on signals from other cells that in their absence they are unable to survive. This is because in the absence of direct cellular interaction or lack of signals as growth factors, cells activate programmed cell death called “apoptosis.”

The cells of a complex animal depend on specific signals coming from the outside even to be fed, because the expression on the cell surface of nutritional conveyors such as amino acids, glucose, etc. Regulated by the action of growth factors. even when the programmed death process is inhibited, for example by removing genes required for apoptosis, private growth factor cells experience progressive atrophy due to energy deficiency, although nutrients are present in the middle that surrounds them.

The first distinction between cellular communication mechanisms can be made based on the chemical properties of the molecules responsible for carrying the message. In the case of water-soluble molecules such as growth factors, peptides and transmitters, they cannot cross the cytoplasmic membrane, and the first component of the transduction system is a surface receptor that couples the signal to its extracellular portion and variously initiates a cascade of events within the cell. If, on the other hand, the chemical messenger is lipid-soluble, as in the case of steroid hormones, it is able to cross the cell membrane and bind to a cytoplasmic receptor.

Such receptors are also transcriptional regulators and, upon binding to their ligand, translocate to the nucleus where they modulate gene expression. Therefore, in the case of lipid-soluble hormones, signal transduction is more direct. Once an external signal is detected by a target cell through the activation of one or more receptors, it must be correctly interpreted to trigger an appropriate intracellular response. Signal transduction or intracellular communication refers to a set of molecular mechanisms that are capable of generating a specific response to an extracellular signal.

In a narrow sense, signal transduction is considered to refer to a messenger, which is significant because they may be a growth factor or cytokine that leads to the formation of a target cell. Generally speaking, we are talking about signal transmission even when specialized cells respond to external stimuli such as light or pressure.

Communication through receptors with tyrosine kinase activity. Cell adhesion as a communication mechanism. Transmembrane domain receptors □ Bibliography. A special case of intercellular communication is the nervous system, a specialized structure for collecting, transmitting and processing information. In this case, cellular communication occurs at specialized joints of cells called synapses. differentiation and can be modified by the same nerve transmission. This phenomenon, known as “synaptic plasticity,” is the basis for the acquisition of information, that is, memory and learning.

Understanding the mechanisms of inter- and intracellular communication requires identifying the components of the system and the rules by which they are related to each other. Although significant progress has been made in recent years in cataloging the various proteins involved in cellular communication, the identification of their interaction networks is still at a preliminary stage. Considering that total number human genes is just over a thousand and that about 60% of them have a recognized function, this means that just under 30% of the human genome is dedicated to inter- and intracellular communication.