TheΔ33-35 Mutantα-Domain Containingβ-Domain-LikeM3S9Cluster Exhibits the Function ofα-Domain withM4S11Cluster in Human Growth Inhibitory Factor

Neuronal growth inhibitory factor (GIF), also known as metallothionein (metallothionein-3), impairs the survival and neurite formation of cultured neurons. It is known that theα-βdomain-domain interaction of hGIF is crucial to the neuron growth inhibitory bioactivity although the exact mechanism is not clear. Herein, theβ(MT3)-β(MT3) mutant and the hGIF-truncatedΔ33-35 mutant were constructed, and their biochemical properties were characterized by pH titration, EDTA, and DTNB reactions. Their inhibitory activity toward neuron survival and neurite extension was also examined. We found that theΔ33-35 mutantα-domain containingβ-domain-likeM3S9cluster exhibits the function ofα-domain withM4S11cluster in hGIF. These results showed that the stability and solvent accessibility of the metal-thiolate cluster inβ-domain is very significant to the neuronal growth inhibitory activity of hGIF and also indicated that the particular primary structure ofα-domain is pivotal to domain-domain interaction in hGIF.