Final answer:
The prion protein, when mutated, can contribute to the development of ataxia by misfolding and causing other proteins to also misfold, ultimately affecting motor function and leading to neurodegenerative diseases.
Step-by-step explanation:
The protein involved in normal immune functions that, if mutated, can cause ataxia, is related to prion proteins. In their normal form, prion proteins may play roles in memory formation and other crucial functions in the central nervous system. However, a mutant version of the prion protein (PrPSc) can misfold and induce other normal proteins to also misfold, leading to the formation of amyloid plaques and neurodegenerative diseases. In the context of ataxia, mutations in specific genes encoding proteins—such as ataxin 1 in Spinocerebellar ataxia (SCA1)—can disrupt motor function by affecting synaptic plasticity in Purkinje cells and altering intracellular calcium levels.