Role and Molecular Regulation of Aquaporins in the Oocyte. In mammalian oocytes, expression of mRNAs encoding different aquaporins has been described (e.g., Edashige et al., 2000), although so far detection of the corresponding polypeptides remained elusive, except for AQP3 in bovine oocytes (Jin et al., 2011).

What is the structure of an aquaporin?

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.

Which expression system of Xenopus is used to express a wide range of proteins?

Which expression system of Xenopus is used to express a wide range of proteins? Clarification: Xenopus oocyte expression system has been a valuable tool for expressing a very wide range of proteins from plants and animals.

What is the dominant secondary structure of the aquaporin protein?

(A) The secondary structure of aquaporins contains six a-helices connected by three extracellular and two intracellular loops. Loops B and E contain NPA motifs and the fifth a-helices contain ar/R motifs, which is described in the text.

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.

What are the function of aquaporin?

The primary function of most aquaporins is to transport water across cell membranes in response to osmotic gradients created by active solute transport.

What are Xenopus oocytes?

The Xenopus oocyte is a unique model system, allowing both the study of complex biological processes within a cellular context through expression of exogenous mRNAs and proteins, and studying the cell, molecular, and developmental biology of the oocyte itself.

Is aquaporin 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 is an aquaporin in 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. Aquaporin monomers assemble as tetramers in membranes, with each monomer functioning independently.

Is aquaporin a gated channel?

In particular, the role of aquaporins as gated ion channels, in addition to their roles as water channels, is likely to have physiological and potentially translational relevance (Yool, 2007a; Yool, 2007c).

What is the definition of aquaporin in biology?

Aquaporins (AQP) are integral membrane proteins that serve as channels in the transfer of water, and in some cases, small solutes across the membrane. They are conserved in bacteria, plants, and animals.