英语翻译这是从一文献中摘抄的,不知其中所指的isoform protein是什么东西?附：Chronic alcohol

英语翻译
这是从一文献中摘抄的,不知其中所指的isoform protein是什么东西?
附：Chronic alcohol misuse by human subjects leads to neuronal loss in regions such as the superior frontal cortex.Reduced GABA transmission may mediate this.The expression of GABAA receptor b1,b2 and b3 isoform proteins was analyzed by western blotting in vulnerable (superior frontal cortex) and spared (primary motor cortex) cortical tissue obtained at autopsy from Caucasian subjects,and the effect of genotypes of candidate genes for alcoholism assessed.