Complex sentence: Gene expression determines protein structures through type II RNA polymerase, hence receptors, neurotransmitter synthesis and breakdown enzymes, and ion channels are each made by from mRNA via DNA transcription of their respective gene.
Split into simpler sentences: Gene expression determines protein structures through type II RNA polymerase. So receptors, neurotransmitter synthesis and breakdown enzymes, and ion channels are each made by from mRNA via the DNA transcription of their respective gene.