because so many of the steps in the dc/4-hp pathway are seen in other pathways, there were only a few unique enzymes to the dc/4-hp pathway, making it difficult to determine the existence of this pathway for a long time. this pathway was only discovered in p. fumarii a few years ago. the dc/4-hp cycle uses the same enzymes to convert oxaloacetate to succinyl-coa and all the same enzymes as the 3-hp/4-hp pathway once the succinate is formed. one molecule that has been identified as being related to hyperthermophilic organisms is di-myo-inositol phosphate (dip). inositol and other phosphate derivatives of this molecule are sugars often used as secondary messenger in eukaryotic cells. however, dip has only ever been found in thermophilic cells and their use within the cells is largely unknown. a derivative of this sugar called udp-α-glcnac3nac-(4←1)-β-glcpnac3nac has been found only in p. fumarii. the function of this sugar is unknown, but phosphorylated forms of this sugar have been found in conjunction with udp-α-glc- nac3nac, which is a sugar known to participate in the formation of the s-layer. these udp sugars are only found when the cells are in supra optimal growing conditions. this suggests that these sugars are building blocks within the cell that allow for the creation of the s-layer protecting gram-positive bacteria. this connection to the s-layer is extremely important, because it is hypothesized that the s-layer is used to help protect the cell from the heat stress associated with hyperthermophilic environments. the s-layer is also thought to help slow molecules from exiting or entering the cell. while these results are not conclusive, they do help to elucidate how the s-layer is created, which has remained a mystery for years.