This image is a scaled-down version of the actual pathway image. It does not contain any links to the protein information pages.
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Description |
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Inorganic sulfur in the environment (primarily sulfate, but also sulfur, and
sulfite) must undergo fixation to be utilized by organisms. The fixation of
sulfate is largely confined to plants and bacteria and biosynthesis of cysteine
represents the final step of sulfate assimilation in these organisms. Fixation
begins with the formation of PAPS (3 -Phosphoadenosine-5 -Phosphosulfate). PAPS
is an activated sulfate compound and an intermediate in all organisms for
sulfate esterification, such as the synthesis of chondroitin sulfate. It is
formed in a two-step reaction from sulfate ion and two molecules of ATP. In
plants, the main pathway of sulfate reduction is via APS
(Adenosine-5 -Phosphosulfate) rather than PAPS (i.e. APS can be utilized
directly, without activation to PAPS, as an intermediary substrate in [...] |
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References:
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