How do different isoforms of pyruvate kinase (PK) regulate glycolysis in various tissues?

Different isoforms of pyruvate kinase (PK) — PKM1, PKM2, PKL, and PKR — enable tissue-specific regulation of glycolytic activity. For instance, PKR is found only in erythrocytes and is crucial for ATP generation in these cells, while PKL is expressed in the liver and kidney. PKM2, associated with cancer, can switch between active and inactive forms depending on cellular conditions, influencing glycolysis rates across various tissues.