Glyconeogenesis
Glyconeogenesis is the synthesis of glycogen without using glucose or other carbohydrates, instead using substances like proteins and fats. This includes substrates like glycerol, lactate, glutamine and alanine.{{cite journal |last1=Jeroundi |first1=Najia |last2=Roy |first2=Charlotte |last3=Basset |first3=Laetitia |last4=Pignon |first4=Pascale |last5=Preisser |first5=Laurence |last6=Blanchard |first6=Simon |last7=Bocca |first7=Cinzia |last8=Abadie |first8=Cyril |last9=Lalande |first9=Julie |last10=Gueguen |first10=Naïg |last11=Mabilleau |first11=Guillaume |last12=Lenaers |first12=Guy |last13=Moreau |first13=Aurélie |last14=Copin |first14=Marie-Christine |last15=Tcherkez |first15=Guillaume |last16=Delneste |first16=Yves |last17=Couez |first17=Dominique |last18=Jeannin |first18=Pascale |title=Glycogenesis and glyconeogenesis from glutamine, lactate and glycerol support human macrophage functions |journal=EMBO Reports |date=18 October 2024 |volume=25 |issue=12 |pages=5383–5407 |doi=10.1038/s44319-024-00278-4 |pmc=11624281 |pmid=39424955 }} It's used in replenishing glycogen stores when glucose is limited,{{cite journal |last1=Park |first1=Hyun-Jun |last2=Jang |first2=Hye Rim |last3=Park |first3=Shi-Young |last4=Kim |first4=Young-Bum |last5=Lee |first5=Hui-Young |last6=Choi |first6=Cheol Soo |title=The essential role of fructose-1,6-bisphosphatase 2 enzyme in thermal homeostasis upon cold stress |journal=Experimental & Molecular Medicine |date=March 2020 |volume=52 |issue=3 |pages=485–496 |doi=10.1038/s12276-020-0402-4 |pmid=32203098 |pmc=7156669 }} like after long periods of fasting.{{cite book |doi=10.1016/C2014-0-01063-5 |title=Biochemistry for Medical Professionals |date=2015 |isbn=978-0-12-801918-4 |first1=Tsugikazu |last1=Komoda |first2=Toshiyuki |last2=Matsunaga }}{{pn|date=May 2025}} In the liver and kidneys, it uses the enzymes phosphoenolpyruvate carboxykinase 2 and fructose-1,6-bisphophatase 1, and fructose-1,6-bisphosphatase 2 in skeletal muscle. One example is the conversion of lactic acid to glycogen in the liver.{{cite book |doi=10.1016/B978-0-12-801918-4.00004-9 |quote=Glyconeogenesis is a shunt for the synthesis of sugars such as glucose and glycogen from substances other than sugars. An example is the conversion from lactic acid to glucose. It passes through the following process, from the lactic acid elevated by a glycolytic shunt to make glucose by glyconeogenesis: lactic acid is converted into alanine and then carried into the liver. Alanine in the liver is changed back to lactic acid and synthesized to glucose by glyconeogenesis. However, glyconeogenesis occurs partly in the kidney. If enzymes are involved in the reaction of the glycolytic shunt, it is possible to make glucose by glyconeogenesis except for three one-way (irreversible) reactions in the glycolytic shunt. |chapter=Metabolic Pathways in the Human Body |title=Biochemistry for Medical Professionals |date=2015 |last1=Komoda |first1=Tsugikazu |last2=Matsunaga |first2=Toshiyuki |pages=25–63 |isbn=978-0-12-801918-4 }} Lactic acid is converted to alanine, the alanine is transferred to the liver, and once in the liver is it converted back to alanine where it is free to be transformed into glucose.