Uroplakin-1b (UP1b), is a

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, respo ...

which in humans is encoded by the ''UPK1B''

gene In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a ba ...

Function

The protein encoded by this gene is a member of the transmembrane 4 superfamily, also known as the

tetraspanin Tetraspanins are a family of membrane proteins found in all multicellular eukaryotes. Tetraspanins, also referred to as the transmembrane 4 superfamily (TM4SF) proteins, have four transmembrane alpha-helices and two extracellular domains, one s ...

family. Most of these members are cell-surface proteins that are characterized by the presence of four hydrophobic

domain Domain may refer to: Mathematics *Domain of a function, the set of input values for which the (total) function is defined **Domain of definition of a partial function **Natural domain of a partial function **Domain of holomorphy of a function * Do ...

s. These proteins mediate

signal transduction Signal transduction is the process by which a chemical or physical signal is transmitted through a cell as a series of molecular events, most commonly protein phosphorylation catalyzed by protein kinases, which ultimately results in a cellula ...

events that play a role in the regulation of cell development, activation, growth and motility. This encoded protein is found in the asymmetrical unit membrane (AUM) where it can form a complex with other transmembrane 4 superfamily proteins. It may play a role in normal bladder epithelial physiology, possibly in regulating

membrane permeability The cell membrane (also known as the plasma membrane (PM) or cytoplasmic membrane, and historically referred to as the plasmalemma) is a biological membrane that separates and protects the interior of all cells from the outside environment (t ...

of superficial umbrella cells or in stabilizing the apical membrane through AUM/

cytoskeletal The cytoskeleton is a complex, dynamic network of interlinking protein filaments present in the cytoplasm of all cells, including those of bacteria and archaea. In eukaryotes, it extends from the cell nucleus to the cell membrane and is compo ...

interactions. The AUM is believed to be involved in strengthening the cells that line the

bladder The urinary bladder, or simply bladder, is a hollow organ in humans and other vertebrates that stores urine from the kidneys before disposal by urination. In humans the bladder is a distensible organ that sits on the pelvic floor. Urine enters ...

, and in enhancing the inner bladder membrane's ability to stretch, thus preventing these cells from rupturing during bladder distension. The use of alternate

polyadenylation Polyadenylation is the addition of a poly(A) tail to an RNA transcript, typically a messenger RNA (mRNA). The poly(A) tail consists of multiple adenosine monophosphates; in other words, it is a stretch of RNA that has only adenine bases. In euk ...

sites has been found for this gene.

Function

References

Further reading