Vitamin B5 (pantothenate) metabolism

Vitamin B5 (pantothenate) metabolism Vitamin B5 ((R)-pantothenate, PanK), is an essential precursor for the synthesis of the metabolic cofactor Coenzyme A (CoA-SH) (Robishaw and Neely 1985) and is the prosthetic group of acyl carrier protein (ACP) (Joshi et al. 2003). The name pantothenate is from the Greek “pantothen”, "from everywhere". Both pantothenate and CoA-SH are found in nearly every foodstuff and in the gut microbiome. CoA-SH itself is readily degraded in the gut and in extracellular fluids within the body. No processes are known to transport it across plasma membranes. Instead, individual cells take up PanK, which is stable in the extracellular environment, to synthesize CoA-SH for their own use. Within a cell, distinct groups of CoA-SH-requiring reactions occur in the cytosol, mitochondrial matrix, and peroxisomes, and controlling CoA pool size in each location plays a major role in regulating and integrating cellular metabolic processes. Control is achieved by selective degradation, synthesis, and transport of CoA within a cell (Cavestro et al. 2023, Naquet et al. 2020). The reactions annotated here provide an incomplete description of these processes, as key steps remain incompletely understood.