Biological membranes

Abstract

For solid-state physicists and engineers the “ultimate in miniaturization” would be to produce devices with structures that are about 8 or 10 nm across—about a tenth of the smallest scale that can currently be produced. (See PHYSICS TODAY, November 1979, page 25.) Biological systems, however, have, in a sense, solved the problems associated with such small microstructures. The fundamental unit of many cell functions, the lipid bilayer membrane (figure 1), is 4 nm thick; in regions where the membrane carries proteins it may be as much as 10 nm thick. Other elements of the cell, such as the microtubules that provide its structural framework, have similar dimensions.

Aquaporins Are Essential to Maintain Motility and Membrane Lipid Architecture During Mammalian Sperm Capacitation

“…Cell homeostasis relies on both the integrity and permeability of plasma membrane to water and electrolytes. Because of its amphipathic nature, additional mechanisms to simple diffusion are required in order for water and solutes to pass through the cell membrane (Watson, 2015). Aquaporins (AQPs) are ubiquitous transmembrane water proteins that allow the transport of water and small solutes across cell membranes (reviewed by Yeste et al, 2017).…”

“…Despite being ubiquitous, the distribution of AQPs across cell types and species is uneven and characteristic. Regarding mammalian sperm, AQP3, AQP7, and AQP11 have been identified in mouse (Yeung et al, 2009;, human Laforenza et al, 2017), pig (Prieto-Martínez et al, 2014, 2015, cattle (Prieto-Martinez et al, 2016;Morató et al, 2018) and horse (Bonilla-Correal et al, 2017); AQP8 has been found in mouse (Yeung et al, 2009) and human spermatozoa Laforenza et al, 2017); and AQP9 has been reported to be present in pig sperm (Vicente-Carrillo et al, 2016). The main functions of AQPs in mammalian spermatozoa are volume regulation and osmoadaptation.…”