An example of an isozyme is glucokinase, a variant of hexokinase which is not inhibited by glucose 6-phosphate. Its different regulatory features and lower affinity for glucose (compared to other hexokinases), allow it to serve different functions in cells of specific organs, such as control of insulin release by the beta cells of the pancreas, or initiation of glycogen synthesis by liver cells. Both these processes must only occur when glucose is abundant.
1.) The enzyme lactate dehydrogenase is a tetramer made of two different sub-units, the H-form and the M-form.  These combine in different combinations depending on the tissue:
2.) Isoenzymes of creatine phosphokinase: Creatine kinase (CK) or creatine phosphokinase (CPK) catalyses the interconversion of phospho creatine to creatine .
CPK exists in 3 isoenzymes. Each isoenzymes is a dimer of 2 subunits M (muscle), B (brain) or both
3.) Isoenzymes of alkaline phosphatase: Six isoenzymes have been identified. The enzyme is a monomer, the isoenzymes are due to the differences in the carbohydrate content (sialic acid residues). The most important ALP isoenzymes are α-ALP, α-heat labile ALP, α-heat stable ALP, pre-β ALP and γ-ALP. Increase in  α-heat labile ALP suggests hepatitis whereas pre-β ALP indicates bone diseases.