GLOSSARY

ADP-Ribosylation transfers an ADP-ribose group to a target.

Adding or removing a chemical group can alter enzyme activity, location, stability or interactions. Phosphorylation is not universally activating; direction depends on protein and site. Acetylation, methylation and small-protein attachment have varied roles and are not all degradation labels. Post-translational changes must be distinguished from new protein production because their speed and persistence can differ, even when they influence the same pathway or exercise response.

Allosteric regulation changes activity through communication between regulatory binding and functional regions; it can activate or inhibit. Feedback carries downstream-product or state information upstream, whereas feedforward conveys input or upstream information onward. Both can operate in one network. Regulation coordinates supply and use rather than keeping every enzyme maximally active, so more activation is not automatically a better nutritional or training outcome.

Enzyme abundance reflects protein synthesis and degradation; gene expression, RNA, protein quantity and measured activity are different layers. Induction and repression need definition because expression and activity can differ. Constitutive does not mean a perfectly constant amount under all conditions. In exercise interpretation, long-term capacity changes must be separated from rapid activation of existing enzyme and from actual pathway flux rather than treating them as interchangeable findings.