Cytosolic peptide:N-glycanase (PNGase, Ngly1) is a de-N-glycosylating enzyme that cleaves N-glycans from glycoproteins. Ngly1 is known to be involved in glycan degradation in the cytosol (non-lysosomal degradation pathway), and endoplasmic reticulum-associated degradation, which is one of the quality control systems for newly synthesized glycoproteins. In 2012, a human subject harboring mutations in the NGLY1 gene was reported (NGLY1-deficiency). Patients with NGLY1-deficiency exhibit severe systemic symptoms, such as global developmental delay, neurological/musculoskeletal deficits, and hypo/alacrima. Thus, it is obvious that Ngly1 has important physiological functions. Nevertheless, how Ngly1 functions in organisms and the precise pathological mechanisms of NGLY1-deficiency remain unclear. This review summarizes recent knowledge of the physiological function of Ngly1 derived from animal models (fly and mouse), and the functional relationship between Ngly1 and nuclear factor erythroid 2-like 1 (NEF2L1, Nrf1).

Marine organisms, especially bivalve molluscs have been known as an alternative source of heparin, an anticoagulant. Although chondroitin sulfate (CS) can be also extracted together with heparin, the detailed glycan structures of CS have not been investigated. CS derived from 11 different shellfish was treated by chondroitinase ABC or chondroitinase ACII, and the resulting unsaturated disaccharides were analyzed by HPLC. As a result, unknown peaks in the chromatograms of some shellfish samples were detected using chondroitinase ACII treatment but not using chondroitinase ABC. In case of CS from Mactra chinensis, keratan sulfate disaccharide substituted at the C-3 position of glucuronic acid was found. These results suggest that disaccharide analysis with chondroitinase ACII is useful for the discovery of structurally unique CS from marine organisms.

Protein O-glucosylation is a class of post-translational modifications that is enzymatically biosynthesized on epidermal growth-factor-like (EGF) repeats of proteins including Notch receptors. Attached to a distinct serine residue within the consensus sequence C¹-X-S-X-(P/A)-C² of EGF repeats, an O-linked glucose (Glc) can be extended by the addition of two xylose (Xyl) residues, forming a linear trisaccharide structure: Xylα1-3Xylα1-3Glcβ1-O-serine residue. A protein O-glucosyltransferase 1 (POGLUT1, Rumi in Drosophila) catalyzes the addition of O-Glc to EGF repeats in the endoplasmic reticulum. POGLUT1/rumi is essential for full Notch activity in mammals and Drosophila. Recent studies have found that mutations in POGLUT1 are linked to human diseases such as Dowling-Degos Disease and a new class of muscular dystrophy.

Cytosolic peptide:N-glycanase (PNGase, Ngly1) is a de-N-glycosylating enzyme that cleaves N-glycans from glycoproteins. Ngly1 is known to be involved in glycan degradation in the cytosol (non-lysosomal degradation pathway), and endoplasmic reticulum-associated degradation, which is one of the quality control systems for newly synthesized glycoproteins. In 2012, a human subject harboring mutations in the NGLY1 gene was reported (NGLY1-deficiency). Patients with NGLY1-deficiency exhibit severe systemic symptoms, such as global developmental delay, neurological/musculoskeletal deficits, and hypo/alacrima. Thus, it is obvious that Ngly1 has important physiological functions. Nevertheless, how Ngly1 functions in organisms and the precise pathological mechanisms of NGLY1-deficiency remain unclear. This review summarizes recent knowledge of the physiological function of Ngly1 derived from animal models (fly and mouse), and the functional relationship between Ngly1 and nuclear factor erythroid 2-like 1 (NEF2L1, Nrf1).

Marine organisms, especially bivalve molluscs have been known as an alternative source of heparin, an anticoagulant. Although chondroitin sulfate (CS) can be also extracted together with heparin, the detailed glycan structures of CS have not been investigated. CS derived from 11 different shellfish was treated by chondroitinase ABC or chondroitinase ACII, and the resulting unsaturated disaccharides were analyzed by HPLC. As a result, unknown peaks in the chromatograms of some shellfish samples were detected using chondroitinase ACII treatment but not using chondroitinase ABC. In case of CS from Mactra chinensis, keratan sulfate disaccharide substituted at the C-3 position of glucuronic acid was found. These results suggest that disaccharide analysis with chondroitinase ACII is useful for the discovery of structurally unique CS from marine organisms.

Protein O-glucosylation is a class of post-translational modifications that is enzymatically biosynthesized on epidermal growth-factor-like (EGF) repeats of proteins including Notch receptors. Attached to a distinct serine residue within the consensus sequence C¹-X-S-X-(P/A)-C² of EGF repeats, an O-linked glucose (Glc) can be extended by the addition of two xylose (Xyl) residues, forming a linear trisaccharide structure: Xylα1-3Xylα1-3Glcβ1-O-serine residue. A protein O-glucosyltransferase 1 (POGLUT1, Rumi in Drosophila) catalyzes the addition of O-Glc to EGF repeats in the endoplasmic reticulum. POGLUT1/rumi is essential for full Notch activity in mammals and Drosophila. Recent studies have found that mutations in POGLUT1 are linked to human diseases such as Dowling-Degos Disease and a new class of muscular dystrophy.