One of the HCV proteases, NS3-4A serine protease, is a non-covalent heterodimer consisting of a catalytic subunit (the N-terminal one-third of NS3 protein) and an activating cofactor (NS4A protein), and is responsible for cleavage at four sites of the HCV polyprotein.

2009年4月21日 · Using constructs that encode the individual West Nile virus (WNV) NS3helicase (NS3hel) and NS3hel linked to the hydrophilic, N-terminal 1–50 sequence of NS4A, we demonstrated that the presence of NS4A allows NS3hel to conserve energy in the course of oligonucleotide substrate unwinding.

2009年6月23日 · In order to study the humoral immune responses against different HCV proteins in patients suffering from chronic HCV infection, we produced three structural (core, E1 and E2) and six nonstructural proteins (NS2, NS3, NS4A, NS4B, NS5A and NS5B) in Sf 9 insect cells by using the baculovirus expression system.

HCV non-structural protein 4A (NS4A) binds to the N-terminal NS3 protease domain to stimulate NS3 serine protease activity. In addition, the NS3 protease domain enhances the RNA binding, ATPase, and RNA unwinding activities of the C-terminal NS3 helicase domain (NS3hel).

NS4A is a cofactor for NS3 that directs the localization of NS3 and modulates its enzymatic activities . The N-terminal one-third of NS3 contains the protease activity responsible for processing of the non-structural region of the polyprotein (Fig. 1b) and some cellular proteins .

NS4A, a 54-amino acid polypeptide, is a cofactor for NS3 protein. The interaction between NS4A and NS3 proteins stabilizes and facilitates its protease activity. The NS3/4A protease is essential for the cleavages of the viral nonstructural proteins.

2009年1月2日 · Here we present the characterization of a single-chain protease in which the NS4A peptide activator is linked to the N-terminus of the NS3 protease domain. This protein behaves well in solution, and its protease activity is very similar to that of full-length NS3-NS4A.

The HCV NS3/4A protein is a membrane-targeted serine protease responsible for maturation of the viral polyprotein, which cleaves four non structural (NS) sites to generate the mature NS3, NS4A, NS4B, NS5A and NS5B proteins.

1998年12月1日 · NS3 forms a tight non-covalent complex with NS4A, a 54 amino acid activator of NS3 protease. Due to the lack of an efficient and robust cell culture system for HCV, genetic knockout experiments which would prove that the NS3 gene of HCV encodes an essential protein have not yet been reported.

The NS4A protein has multiple functions in the HCV life cycle, including (1) anchoring the NS3-4A complex to the outer leaflet of the endoplasmic reticulum and mitochondrial outer membrane, (2) serving as a cofactor for the NS3A serine protease, (3) augmenting NS3A helicase activity, and (4) regulating NS5A hyperphosphorylation and viral ...