Sodium/glucose cotransporter 1 is a protein

Protein

Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...

 that in humans is encoded by the SLC5A1 gene

Gene

A gene is a molecular unit of heredity of a living organism. It is a name given to some stretches of DNA and RNA that code for a type of protein or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains...

.

Cloning of the sodium-glucose cotransporter SGLT1

Co-transport proteins of mammalian cell membranes had eluded efforts of purification with classical biochemical methods until the late 1980s. These proteins had proven difficult to isolate because they contain hydrophilic and hydrophobic sequences and exist in membranes only in very low abundance (<0.2% of membrane proteins). The rabbit form of SGLT1 is the first mammalian co-transport protein ever to be cloned and sequenced, and this scientific break-through was reported in 1987. To circumvent the difficulties with traditional isolation methods, Swiss-born biochemist Matthias Hediger and his collaborators at UCLA used a novel technique of expression cloning

Expression cloning

Expression cloning is a technique in DNA cloning that uses expression vectors to generate a library of clones, with each clone expressing one protein. This expression library is then screened for the property of interest and clones of interest recovered for further analysis...

. They size-fractionated large amounts of rabbit intestinal mRNA with a preparative gel electrophoresis device developed by Hediger. These size fractions were then sequentially injected into Xenopus

Xenopus

Xenopus is a genus of highly aquatic frogs native to Sub-Saharan Africa. There are 19 species in the Xenopus genus...

oocytes to ultimately find the RNA species that induced the expression of sodium-glucose cotransport.

Further reading