title: Addition of beta1-6 GlcNAc branching to the oligosaccharide attached to Asn 772 in the serine protease domain of matriptase plays a pivotal role in its stability and resistance against trypsin.
abstract: beta1-6 GlcNAc branching, a product of N-acetylglucosaminyltransferase V (GnT-V), is a key structure that is associated with malignant transformations and cancer metastasis. Although a number of reports concerning tumor metastasis-related glycoproteins that contain beta1-6 GlcNAc branching have appeared, the precise function of beta1-6 GlcNAc branching on glycoproteins remains to be elucidated. We previously reported on the importance of beta1-6 GlcNAc branching on matriptase in terms of proteolytic degradation in tumor metastasis. We report here that matriptase purified from GnT-V transfectant (beta1-6 GlcNAc matriptase) binds strongly to L4-PHA, which preferentially recognizes beta1-6 GlcNAc branches of tri- or tetraantennary sugar chains, indicating that the isolated matriptase contains beta1-6 GlcNAc branching. The beta1-6 GlcNAc matriptase was resistant to autodegradation, as well as trypsin digestion, compared with matriptase purified from mock-transfected cells. Furthermore, N-glycosidase-F treatment of beta1-6 GlcNAc matriptase greatly reduced its resistance to degradation. An analysis of matriptase mutants that do not contain potential N-glycosylation sites clearly shows that the beta1-6 GlcNAc branching on N-glycans attached to Asn 772 in the serine protease domain plays a major role in trypsin resistance. This is the first example of a demonstration of a direct relationship between beta1-6 GlcNAc branching and a biological function at the protein level.
authors.affiliation: Department of Biochemistry, Osaka University Graduate School of Medicine, B1, 2-2, Yamadaoka, Suita, Osaka 565-0871, Japan.
authors.forename: Shinji
authors.initials: S
authors.lastname: Ihara
authors.forename: Eiji
authors.initials: E
authors.lastname: Miyoshi
authors.forename: Susumu
authors.initials: S
authors.lastname: Nakahara
authors.forename: Haruhiko
authors.initials: H
authors.lastname: Sakiyama
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Ihara
authors.forename: Ayumi
authors.initials: A
authors.lastname: Akinaga
authors.forename: Koichi
authors.initials: K
authors.lastname: Honke
authors.forename: Robert B
authors.initials: RB
authors.lastname: Dickson
authors.forename: Chen-Yong
authors.initials: CY
authors.lastname: Lin
authors.forename: Naoyuki
authors.initials: N
authors.lastname: Taniguchi
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D019556:COS Cells; D045744:Cell Line, Tumor; D016895:Culture Media, Serum-Free; D006031:Glycosylation; D006801:Humans; D037102:Lectins / Q000378:metabolism; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009362:Neoplasm Metastasis; D009844:Oligosaccharides / Q000737:chemistry; D012697:Serine Endopeptidases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D014162:Transfection; D014357:Trypsin / Q000494:pharmacology*
chemical_list: D016895:Culture Media, Serum-Free; D037102:Lectins; D009844:Oligosaccharides; D012697:Serine Endopeptidases; C485595:matriptase; C485596:ST14 protein, human; D014357:Trypsin