Tether (cell biology)

{{Short description|Form of cell surface protrusion}}

{{Other uses|tether}}{{Distinguish|Membrane contact site}}{{One source|date=May 2025}}

{{Split|date=May 2024|Tether (Cell biology)|Tether (Biochemistry)|discuss=Talk:Tether (cell biology)#Split proposed}}

A tether is a form of cell surface protrusion, separated from the cytoskeleton after the application of low pulling forces to the cell surface membrane. They are thin, viscoelastic tubes which can be observed in vivo due to shear flow caused by molecular bonds between blood cells and vessel walls, for example.{{Cite journal |last1=Pospieszalaska |first1=Maria K. |last2=Lasiecka |first2=Irena |last3=Ley |first3=Klaus |date=6 April 2011 |title=Cell Protrusions and Tethers: A Unified Approach |journal=Biophysical Journal |volume=100 |issue=7 |pages=1679–1707 |doi=10.1016/j.bpj.2011.02.038 |pmid=21463583 |pmc=3072668 |bibcode=2011BpJ...100.1697P }}

In biochemistry, a tether is a molecule that carries one or two carbon intermediates from one active site to another. They are commonly used in lipid synthesis, gluconeogenesis, and the conversion of pyruvate into Acetyl CoA via PDH complex. Common tethers are lipoate -lysine residue complex associated with dihydrolipoyl transacetylase, which is used for carrying hydroxyethyl from hydroxyethyl TPP. This compound forms Acetyl- CoA, a convergent molecule in metabolic pathways.{{Citation needed|date=May 2024}}

Another tether is biotin-lysine residue complex associated with pyruvate carboxylase, an enzyme which plays an important role in gluconeogenesis. It is involved in the production of oxaloacetate from pyruvate.{{Citation needed|date=May 2024}}

One of the biological tethers used in the synthesis of fats is a β- mercaptoethylamine-pantothenate complex associated with an acyl carrier protein.{{Citation needed|date=May 2024}}