sentence: Based on multiple reaction monitoring , the four most abundant types identified in WT and sbh protonemata included those having two saccharide units ( Series A ) , HexN ‐ GlcA ‐ IPC , Hex ‐ GlcA ‐ IPC , and HexNAc ‐ GlcA ‐ IPC , and one having three saccharide units ( series B ) , Hex ‐ Hex ‐ GlcA ‐ IPC .