HBV preS

The HBV surface protein antigens (HBsAg) are comprised of three carboxyl co terminal HBs proteins termed large (LHBs), middle (MHBs) and small (SHBs, also called major) protein. LHBs and MHBs also share the highly hydrophobic, repetitive, membrane spanning S domain. LHBs is the largest of the HBV surface proteins, containing the Pre-S1 domain as well as the Pre-S2 and S domains. The Pre-S1 domain's sequence appears to be highly variable among infected patients, suggesting that this may be the HBV protein involved in liver attachment. The Pre-S1 domain contains no additional glycosylation sites, but contains a myristylation signal at its N-terminus, anchoring the N-terminus to the membrane.