Glycolytic enzyme the catalyzes the conversion of 2-phosphoglycerate to phosphoenolpyruvate (By similarity). In addition to glycolysis, involved in various processes such as growth control, hypoxia tolerance and allergic responses (PubMed:7499243). May also function in the intravascular and pericellular fibrinolytic system due to its ability to serve as a receptor and activator of plasminogen on the cell surface of several cell-types such as leukocytes and neurons (By similarity). Stimulates immunoglobulin production (By similarity). (2R)-2-phosphoglycerate = H2O + phosphoenolpyruvate Binds two Mg(2+) per subunit. Required for catalysis and for stabilizing the dimer. Carbohydrate degradation; glycolysis; pyruvate from D-glyceraldehyde 3-phosphate: step 4/5. Mammalian enolase is composed of 3 isozyme subunits, alpha, beta and gamma, which can form homodimers or heterodimers which are cell-type and development-specific. ENO1 interacts with PLG in the neuronal plasma membrane and promotes its activation. The C-terminal lysine is required for this binding. Interacts with ENO4 and PGAM2 (By similarity). Interacts with CMTM6 (By similarity). Can translocate to the plasma membrane in either the homodimeric (alpha/alpha) or heterodimeric (alpha/gamma) form. ENO1 is localized to the M-band. The alpha/alpha homodimer is expressed in embryo and in most adult tissues. The alpha/beta heterodimer and the beta/beta homodimer are found in striated muscle, and the alpha/gamma heterodimer and the gamma/gamma homodimer in neurons. During ontogenesis, there is a transition from the alpha/alpha homodimer to the alpha/beta heterodimer in striated muscle cells, and to the alpha/gamma heterodimer in nerve cells. Expression increased up to 3-fold by hypoxic stress in vascular endothelial cells. ISGylated. Lysine 2-hydroxyisobutyrylation (Khib) by p300/EP300 activates the phosphopyruvate hydratase activity. Belongs to the enolase family.