Introduction

 The Importance of Bile acids

Bile acids are synthesised from cholesterol in the liver and have multiple functions; they can induce multiple pathways and processes (i.e. electrolyte absorption and triggering apoptosis).

Bile acids aid in the absorption of lipids, cholesterol and any lipid soluble vitamins. They can transport these substrates due to their amphipathic nature, allowing them to form micelles to shield hydrophobic regions. At physiological pH it is an impermeable ion. It requires specialised transporters to pass through the ileum membrane. {{88 Alrefai,Waddah A. 2007}}

Location of ASBT in the Ileal Enterocyte

{{93 Zhang,EY 2002}}

Some structures that are involved in bile acids transportation are: NA²⁺ Taurocholate cotransporter polypeptide (NTCP) and apical sodium dependant bile acid transporter (ASBT). Many more transporters are involved in regulating the levels of bile acids in the body; either by absorption, enterohepatic cycling or cholesterol homeostasis. We will be focussing on the structure and function of the transporter ASBT. {{90 Dawson,Paul A. 2009}}

Examples of different bile acids, shown in the name is the position of the steroid's hydroxyl group.