Crystal Structure of Human Trypsin 1: Unexpected Phosphorylation of Tyr151

Gaboriaud, Christine; Serre, Laurence; Guy-Crotte, Odette; Forest, Éric; Fontecilla‐Camps, J.C.

doi:10.1006/jmbi.1996.0376

Cited by 81 publications

(77 citation statements)

References 31 publications

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“…Trypsin is a 24 kDa endopeptidase commonly produced in the pancreas for the digestion of dietary amino acids (69). It cleaves a wide range of proteins at the C-terminus of lysine or arginine except when followed by a proline residue.…”

Section: Models Of Osteoarthritis In Articular Cartilagementioning

confidence: 99%

Sodium and T_1ρ MRI for molecular and diagnostic imaging of articular cartilage

et al. 2006

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In this article, both sodium magnetic resonance (MR) and T 1r relaxation mapping aimed at measuring molecular changes in cartilage for the diagnostic imaging of osteoarthritis are reviewed. First, an introduction to structure of cartilage, its degeneration in osteoarthritis (OA) and an outline of diagnostic imaging methods in quantifying molecular changes and early diagnostic aspects of cartilage degeneration are described. The sodium MRI section begins with a brief overview of the theory of sodium NMR of biological tissues and is followed by a section on multiple quantum filters that can be used to quantify both bi-exponential relaxation and residual quadrupolar interaction. Specifically, (i) the rationale behind the use of sodium MRI in quantifying proteoglycan (PG) changes, (ii) validation studies using biochemical assays, (iii) studies on human OA specimens, (iv) results on animal models and (v) clinical imaging protocols are reviewed. Results demonstrating the feasibility of quantifying PG in OA patients and comparison with that in healthy subjects are also presented. The section concludes with the discussion of advantages and potential issues with sodium MRI and the impact of new technological advancements (e.g. ultra-high field scanners and parallel imaging methods). In the theory section on T 1r , a brief description of (i) principles of measuring T 1r relaxation, (ii) pulse sequences for computing T 1r relaxation maps, (iii) issues regarding radio frequency power deposition, (iv) mechanisms that contribute to T 1r in biological tissues and (v) effects of exchange and dipolar interaction on T 1r dispersion are discussed. Correlation of T 1r relaxation rate with macromolecular content and biomechanical properties in cartilage specimens subjected to trypsin and cytokineinduced glycosaminoglycan depletion and validation against biochemical assay and histopathology are presented. Experimental T 1r data from osteoarthritic specimens, animal models, healthy human subjects and as well from osteoarthritic patients are provided. The current status of T 1r relaxation mapping of cartilage and future directions is also discussed. Copyright # 2006 John Wiley & Sons, Ltd. KEYWORDS: cartilage; arthritis; spin-lock; T1rho; sodium; MRI OSTEOARTHRITIS Osteoarthritis (OA) affects more than half of the population above the age of 65 (1,2) and has a significant negative impact on the quality of life of elderly individuals (3). The economic costs in the USA from OA have been estimated to be more than 1% of the gross domestic product (4). OA is now increasingly viewed as a metabolically active joint disorder of diverse etiologies. The biochemistry of the disease is characterized by the following changes in cartilage: reduced proteoglycan (PG) concentration, possible changes in the size of collagen fibril and aggregation of PG, increased water content and increased rate of synthesis and degradation of matrix macromolecules. The earliest changes in the cartilage due to OA result in a partial breakdown in the proteoglyc...

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Section: Models Of Osteoarthritis In Articular Cartilagementioning

confidence: 99%

Sodium and T_1ρ MRI for molecular and diagnostic imaging of articular cartilage

et al. 2006

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“…Most importantly, as in the case of the bovine 33 and porcine 34 trypsinogens, residue R122 of the human cationic trypsinogen was identified to be the primary autolysis site by co-sequencing of the first 14 residues of the partially proteolysed protein. 35 Protection of this autolysis site by a monoclonal antibody against human cationic trypsinogen resulted in increased enzyme activity, 35,36 and substitution of this site with certain amino acids, 37,38 especially histidine 39 in the rat trypsinogen showed increased enzyme stability. Thus, the pathogenesis of the R122H mutation, considered in connection with the existing theory of pancreatitis, the basic biochemistry and physiology of trypsinogen, and combined with the molecular modelling and X-ray crystallography data provided in the original paper by Whitcomb et al, 7 is clear and evident.…”

Section: R122h (R117h)mentioning

confidence: 99%

“…Since R122 has been confirmed to be the primary autolysis site 35 and trypsin specifically catalyses the hydrolysis of peptide bonds on the carboxyl side of arginine (R) and lysine (K) residues, we surmise that in vitro experiments on the human R122H mutant would not yield any more useful information beyond these fundamental observations. Transgenic models are attractive but certainly will be confounded by the existence of multiple functional trypsinogen genes and different protective mechanisms against trypsinogen activation in mice.…”

Section: R122h (R117h)mentioning

confidence: 99%

“…In support of this, the physico-chemical characteristics of Ile are quite different from those of Asn, and a structural difference for Figure 1 A unifying model of the R122H and N29I mutations in the pathogenesis of HP. This model is based mainly on the observations that R122 is the primary autolysis site of the cationic trypsinogen, 35 thereby constituting the unique 'self-destruct' defence system of the body against pancreatic autodigestion, 7 and that N29 is near R122 on the trypsin surface. 35 Arrows indicate the accessibility of trypsin-like enzymes to residue 122.…”

Section: N29i (N21i)mentioning

confidence: 99%

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Molecular basis of hereditary pancreatitis

Chen¹,

Férec²

2000

Eur J Hum Genet

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Hereditary pancreatitis (HP) is an autosomal dominant disease. Two heterozygous missense mutations, R122H (R117H) and N29I (N21I), in the cationic trypsinogen gene have been clearly associated with HP. The 'self-destruct' model proposed for the R122H mutation is discussed in connection with the existing theory of pancreatitis, and the basic biochemistry and physiology of trypsinogen, with particular reference to R122 as the primary autolysis site of the cationic trypsinogen. Two different genetic mechanisms are identified which cause the R122H mutation, and gene conversion is the likely cause of the N29I mutation. A unifying model, which highlights an indirect impairment on the R122 autolysis site is hypothesised for the N29I mutation. Possible predisposition to pancreatitis by additional DNA variants in the gene, such as the A16V signal peptide cleavage site mutation and the K23R activation peptide cleavage site mutation is suspected, but not proven. Evidence of genetic heterogeneity of HP is reviewed and cystic fibrosis transmembrane conductance regulator (CFTR) gene mutations detected in HP families are re-evaluated. Finally, large scale association studies are expected to clarify the additional variants' role in pancreatitis and to identify new HP genes.

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“…In E. coli cytoplasmic aminopeptidases can trim the N terminus of recombinant trypsinogens, whereas in human acinar cells trypsinogens get post-translationally modified on Tyr154. This modification was originally described as phosphorylation [19], but more recent data suggest that the modifying group is a sulfate [M. S.-T., unpublished observation]. Post-translational sulfation is absent in E. coli.…”

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confidence: 99%

Biochemical Models of Hereditary Pancreatitis

Sahin–Tóth

2006

Endocrinology and Metabolism Clinics of North America

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The past decade has witnessed remarkable progress in the genetics of chronic pancreatitis. Mutations of the PRSS1 gene encoding cationic trypsinogen and the SPINK1 gene encoding pancreatic secretory trypsin inhibitor were found in association with hereditary, familial or sporadic chronic pancreatitis; and the genotype -phenotype correlations have been characterized at the clinical level. Despite these accomplishments, our understanding of the molecular mechanism(s) through which PRSS1 and SPINK1 mutations cause chronic pancreatitis has remained sketchy. Pancreatitis-associated gene mutations are believed to result in uncontrolled trypsin activity in the pancreas. Thus, PRSS1 mutations would cause a gain of (trypsin) function, while SPINK1 mutations would result in the loss of a (trypsin inhibitor) function. However, experimental identification of the disease-relevant functional alterations caused by PRSS1 or SPINK1 mutations proved to be challenging, as results of biochemical analyses lent themselves to different interpretations. The present review focuses on PRSS1 mutations and summarizes the salient biochemical findings in the context of the mechanistic models that attempt to explain the connection between mutations and hereditary pancreatitis. Human Trypsinogens and Pancreatitis-Associated Trypsinogen MutationsThe human pancreas produces the digestive pro-enzyme trypsinogen in three isoforms. On the basis of their relative isoelectric points and electrophoretic mobility, these are commonly referred to as cationic trypsinogen, anionic trypsinogen, and mesotrypsinogen. The isoenzymes are encoded by separate genes, the PRSS1 (protease, serine, 1), PRSS2 and PRSS3 genes (for a recent review see [1] and references therein). Cationic trypsinogen (PRSS1) and anionic trypsinogen (PRSS2) make up the bulk of secreted trypsinogens in the pancreatic juice, while mesotrypsinogen (PRSS3) accounts for 2-10 % [2-6]. Typically, there is approximately twice as much cationic trypsinogen as anionic trypsinogen, but this ratio is reversed in chronic alcoholism or chronic pancreatitis [3,5]. The significance of the "isoform reversal" is unknown [7]. Human trypsinogens are synthesized as pre-pro-enzymes with a signal peptide of 15 amino acids, followed by the 8 amino acid long pro-peptide, the trypsinogen activation peptide. The signal-peptide is removed upon entry into the endoplasmic reticulum lumen and the proenzymes are packaged into zymogen granules and eventually secreted into the pancreatic juice. Physiological activation of trypsinogen to trypsin takes place in the duodenum by enteropeptidase (enterokinase), a highly specialized serine protease in the brush-border membrane of enterocytes. Trypsin can also activate trypsinogen, a process termed autoactivation, which in the duodenum may have a physiological role in facilitating zymogen activation, whereas inappropriate autoactivation in the pancreas might cause pancreatitis. Mutations in the PRSS1 gene have been identified in patients with hereditary pancreatitis, fam...

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Crystal Structure of Human Trypsin 1: Unexpected Phosphorylation of Tyr151

Cited by 81 publications

References 31 publications

Sodium and T_1ρ MRI for molecular and diagnostic imaging of articular cartilage

Sodium and T_1ρ MRI for molecular and diagnostic imaging of articular cartilage

Molecular basis of hereditary pancreatitis

Biochemical Models of Hereditary Pancreatitis

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Crystal Structure of Human Trypsin 1: Unexpected Phosphorylation of Tyr151

Cited by 81 publications

References 31 publications

Sodium and T1ρ MRI for molecular and diagnostic imaging of articular cartilage

Sodium and T1ρ MRI for molecular and diagnostic imaging of articular cartilage

Molecular basis of hereditary pancreatitis

Biochemical Models of Hereditary Pancreatitis

Contact Info

Product

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Sodium and T_1ρ MRI for molecular and diagnostic imaging of articular cartilage

Sodium and T_1ρ MRI for molecular and diagnostic imaging of articular cartilage