Transmembrane protein

Structure of Tight Junctions and their Dynamic Functions in Health and Disease Tight junction (TJ) discovery in the 1960s helped determine the nature of paracellular transport while the discovery of their constituting proteins subsequently improved understanding of TJs’ dynamic structure. Their role can be appreciated particularly in epithelial cells and when their formation is compromised; I aim to briefly explore the cause of Crohn’s disease to illustrate this. Furthermore, I will outline the key structural components of TJs which make them dynamic across different tissues using the blood-brain barrier as an example meanwhile discussing some ambiguities that require further research. TJs play vital roles in paracellular transport (movement of substances via gaps between cells) (Anderson, Van Itallie 2007). They are localised at the most apical point of the intracellular cleft to separate the apical and basolateral compartments (see fig. 1 – FIG 19-2 BIG TEXTBOOK) so larger molecules (>15Å sometimes >60Å) are forced to pass through transporter proteins embedded in the epithelial cells using transcellular pathways (intracellular movement of substances) (Anderson, Van Itallie 2007). These transporter proteins must navigate to either the apical or basal regions of epithelia and TJs aid…

Efflux is a method of facilitated transport carried out by protein complexes that fall into one of six currently identified classes based on their protein structure.44 These complexes are commonly able to recognize more than one substrate, making them a major cause of multidrug resistance, especially in Gram negative organisms.45 As many of these proteins are not expressed constitutively, it may be hard to predict the effect these complexes have on in-vivo treatment; many are tightly regulated…

through the plasma membrane. In reality, the Blob would have problems maintaining sufficient transport and would suffer from malnutrition. The size of a cell determines the amount of nutrients, water, and oxygen needed, therefore, the volume of a cell must be just right to sustain life and function. More demand would be placed on DNA for indefinitely growing cells because more protein production would be necessary for cellular function. Furthermore, more transcribed DNA to mRNA would lead to the…

Physiology Textbook 66) There are two general membrane proteins, including the integral proteins, also known as transmembrane proteins. These proteins act as transporters, channels and receptors. "Integral proteins are…

Insulin Receptor Introduction Insulin receptor (IR) is a transmembrane receptor, an important member to a large family of tyrosine kinase receptor proteins. Endogenous ligands such as insulin, IGF-1 (Insulin-like growth factor-1) and IGF-2 (Insulin-like growth factor-2) bind to this receptor to carry out major physiological and metabolic functions. INSR (Insulin Receptor) gene encodes a preproprotein that is proteolytically processed in our body to form a functional heterotetrameric insulin…

a) Cystic fibrosis affects ion transport in what type of cells? (1 mark) Cystic fibrosis affects ion transport in epithelial cells b) The CFTR protein regulates the transport of a number of ions; name 2 of these ions. (2 marks) The CFTR protein regulates the transport of Cl- and Na+ c) Explain why a defective CFTR gene could cause Dan to produce very salty sweat. (5 marks) The normal function of the CFTR gene provides instructions for making a protein channel called the cystic fibrosis…

where it acts as a proton-pump, transporting protons out of the cell. Since its discovery in 1979, much research has been done on Bacteriorhodopsin and there have been many advancements in our knowledge. Firstly, on its structure and function and secondly, on the conformational changes it undergoes during retinal isomerisation. Introduction Bacteriorhodopsin is a globular protein, (Henderson, 1975) which acts as a light driven proton- pump located in the native purple membrane of Halobacterium…

and floor plate cells to differentiate.7 The expression of Shh can be found in the floor plate after the Shh signaling in the notochord. 8 The study of Shh has been made easier by its homolog in the Drosophila melanogaster.9 . . . . . . . . . . .. . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Within the diencephalon, the Zona limitans intrathalamica secrets the Shh protein which patterns cells close to it and influences cells to later become…

This property distinguishes them from small, monomeric G proteins. The guanine nucleotide-binding site is present on the G subunit. Replacement of GDP by GTP, following interaction with an activated GPCR, results in a conformational change in the G subunit. In its GTP-bound conformation, the G subunit has a low affinity for G, leading to its dissociation from the complex. Each dissociated G subunit (with GTP attached) is free to activate an effector protein, such as adenyl cyclase as shown in the…

Receptors are protein molecules that receive chemical signals in the form of ligands and induce responses at cellular level. They are localized at the cell surface, cytoplasm or the nucleus, depending on their amino acid sequences. In addition to using these three different localizations to categorize receptors, the types of action of receptors are also used as a mean of classification. The four main classifications of receptors are: 1. Ionotropic (or ligand-gated ion channel) receptors, 2.…