What is the structure of aquaporins?
Aquaporin proteins are composed of a bundle of six transmembrane α-helices. They are embedded in the cell membrane. The amino and carboxyl ends face the inside of the cell. The amino and carboxyl halves resemble each other, apparently repeating a pattern of nucleotides.
What protein structure is aquaporin?
Abstract. The aquaporins (AQPs) are a family of small membrane-spanning proteins (monomer size ∼30 kDa) that are expressed at plasma membranes in many cells types involved in fluid transport.
Do aquaporins have a tertiary structure?
The crystal structures of aquaporins from several species show that their tertiary structures comprise six transmembrane helices plus a pseudo helix, made up of two aligned half-helices inserted from opposite sides of the membrane, arranged to form a pore through which water can flow (Figure 1).
What are the characteristics of an aquaporin protein?
Aquaporins (AQPs ) are a class of the integral membrane proteins, which are permeable to water , some small neutral solutes and certain gases across biological membranes.
What is the role of aquaporins in the kidney?
Aquaporins (AQPs) are a newly recognized family of transmembrane proteins that function as molecular water channels. At least four aquaporins are expressed in the kidney where they mediate rapid water transport across water-permeable epithelia and play critical roles in urinary concentrating and diluting processes.
Where are aquaporins found in the kidney?
Aquaporin-1 (AQP1) is extremely abundant in the proximal tubule and descending thin limb where it appears to be the main site for proximal nephron water reabsorption. It is also present in the descending vasa recta.
What is the function of aquaporin?
Aquaporins are membrane channels expressed in almost every organism and involved in the bidirectional transfer of water and small solutes across cell membranes.
Are aquaporins polar or nonpolar?
Aquaporins have nonpolar parts because this allows them to embed in the membrane.
Are aquaporins facilitated diffusion?
Water can pass through biological membranes via two pathways: simple diffusion through the lipid bilayer, or water-selective facilitated diffusion through aquaporins (AQPs).
What are the types of aquaporin?
Human contains 13 AQPs (AQP0–AQP12) which are divided into three sub-classes namely orthodox aquaporin (AQP0, 1, 2, 4, 5, 6, and 8), aquaglyceroporin (AQP3, 7, 9, and 10) and super or unorthodox aquaporin (AQP11 and 12) based on their pore selectivity.
What is an aquaporin biology?
Aquaporins (often called aquaporin water channels) are a family of small, integral membrane proteins that are expressed broadly throughout the animal and plant kingdoms.
Can aquaporin-based proteoliposomes be used for seawater desalination?
Effects of proteoliposome composition and draw solution types on separation performance of aquaporin-based proteoliposomes: implications for seawater desalination using aquaporin-based biomimetic membranes Aquaporins are a large family of water transport proteins in cell membranes.
What is the single channel water permeability of aquaporin?
The intrinsic “single-channel” aquaporin water permeability can be computed from proteoliposome size, the kinetics of volume change following an osmotic challenge, and the amount of aquaporin protein in the proteoliposome. The single-channel water permeability of AQP1 was determined to be ∼6 × 10 −14 cm 3 /s ( 100 ).
What are the basic features of aquaporin structure?
Basic features of aquaporin structure have been defined using mutagenesis, epitope tagging, and spectroscopic and freeze-fracture electron microscopy methods.
What is the aquaporin family?
the aquaporin family of water channels consists of 10 proteins cloned from mammals and many more from amphibians, plants, yeast, bacteria, and various lower organisms.