Complex sentence: A prototypical eight TMS topology apparently arose by intragenic duplication of a four transmembrane segment (TMS) unit, and possibly, a two TMS α-helical hairpin structure was the precursor of the 4 TMS repeat unit.
Split into simpler sentences: A prototypical eight TMS topology apparently arose by intragenic duplication of a four transmembrane segment (TMS) unit. Possibly, a two TMS α-helical hairpin structure was the precursor of the 4 TMS repeat unit.