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J R Yates

Publications and source records attributed to J R Yates.

At least 19 recordsLinked to original sources
PubMed1992

Complete enzymatic deglycosylation of native sex steroid-binding protein (SBP or SHBG) of human and rabbit plasma: effect on the steroid-binding activity.

An enzymatic procedure for the complete removal of the N-linked and O-linked oligosaccharide side chains of the sex steroid-binding proteins (SBP or SHBG) of human and rabbit plasma under native conditions is described. Deglycosylation was catalyzed by N-glycanase, neuraminidase, and O-glycanase and was monitored by SDS-PAGE, lectin blotting, and molecular weight analyses by electrospray mass spectrometry. Digestion of rabbit SBP with N-glycanase generated a major 39,777-Da protein and two minor ones of 39,389 and 39,545 Da. The molecular weight of the major protein agrees with the molecular weight calculated from the sequence of the sugar-free polypeptide monomer (39,769 Da: Griffin, P.R., Kumar, S., Shabanowitz, J., Charbonneau, H., Namkung, P.C., Walsh, K.A., Hunt, D.F., & Petra, P.H., 1989, J. Biol. Chem. 264, 19066-19075), whereas the other two are deglycosylated proteolytic cleavage products lacking the TQR and TQ sequences at the amino-terminus. The N- and O-linked side chains of human SBP were removed by sequential digestion with N-glycanase and neuraminidase/O-glycanase. A 38,771-Da protein was generated, which agrees well with the molecular weight of the sugar-free polypeptide monomer (Walsh, K.A., Titani, K., Kumar, S., Hayes, R., & Petra, P.H., 1986, Biochemistry 25, 7584-7590). N-deglycosylation of human and rabbit SBP has no effect on the steroid-binding activity, but removal of the O-linked side chains of N-deglycosylated human SBP results in an apparent 50% loss of steroid-binding activity and an increase in the Kd for the binding of 5 alpha-dihydrotestosterone from 0.3 mM to 0.9 nM.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Genetic counselling in X-linked ocular albinism: clinical features of the carrier state.

Forty-nine obligate heterozygotes and 64 at risk females were assessed from 17 families affected by X-linked ocular albinism to determine the relative values of clinical examination and skin biopsy in carrier detection. 92% of obligate heterozygotes had a mud-splattered appearance of the fundus with hyperpigmented streaks and in 74% this was associated with marked iris translucency. Skin histology showed macromelanosomes in 84%. 27 of 64 (42%) at risk females had definite features of the carrier state and 19 (30%) were unequivocally normal but a further 18 (28%) had mild RPE abnormalities, often with iris transillumination defects, of uncertain significance. Fundus examination will detect most carrier females but will not allow reliable genetic counselling for all at risk females, even when supplemented by skin biopsy.

Albinism, Ocular↗
PubMed1992

Presymptomatic diagnosis of von Hippel-Lindau disease with flanking DNA markers.

Von Hippel-Lindau (VHL) disease is a dominantly inherited cancer syndrome characterised by the development of retinal, cerebellar, and spinal haemangioblastomas, renal cell carcinoma, and phaeochromocytoma. The gene for VHL disease has been mapped to chromosome 3p25-p26 and flanking markers identified. We have investigated the usefulness of currently available DNA markers for the presymptomatic diagnosis of VHL disease. In the first part of this investigation, genetic linkage data from two previously published studies were updated and reanalysed to provide accurate estimates of sex specific recombination fractions and to confirm that there is no evidence of locus heterogeneity. In the second part of this study, 14 families containing 23 asymptomatic subjects at 50% prior risk of VHL disease were investigated with closely linked DNA markers (RAF1, D3S18, D3S732). Seventeen subjects were informative with one or more markers, six of whom were informative at markers flanking the VHL disease gene. By combining age related and DNA based risk information the carrier risk for 11 subjects was reduced to < 2%.

Adolescent↗
PubMed1992

Genetic mapping of X linked ocular albinism: linkage analysis in British families.

Genetic linkage studies were performed in 16 British families affected by X linked ocular albinism (XLOA) using RFLPs from the Xp22.3 region. Linkage was confirmed between the XLOA locus (OA1) and the loci DXS143 (dic56; Zmax = 15.90 at theta = 0.0, confidence interval (CI) 0-0.035), DXS85 (782; Zmax = 15.67 at theta = 0.04, CI = 0.007-0.11), and DXS237 (GMGX9; Zmax = 12.65 at theta = 0.08, CI = 0.03-0.17). Multipoint linkage analysis placed OA1 between DXS85 (782) and DXS237 (GMGX9) with odds exceeding 10(4):1 to give the map DXS85-(OA1,DXS143)-DXS237-XG-Xpter. OA1 lies close to DXS143 (dic56) but in the absence of recombinants the order of these loci could not be determined.

Albinism, Ocular↗
PubMed1991

Aspartylglycosaminuria in the Finnish population: identification of two point mutations in the heavy chain of glycoasparaginase.

Aspartylglycosaminuria is an inherited lysosomal storage disease caused by deficiency of glycoasparaginase (EC 3.5.1.26) and occurs with higher frequency among Finns than other populations. We have purified human glycoasparaginase and determined about 90% of the amino acid sequence of its light subunit and greater than 70% of that of its heavy subunit by Edman degradation and mass spectrometry. Additional sequence data were obtained from the cloning and subsequent nucleotide analysis of a cDNA corresponding to the normal human glycoasparaginase gene. The enzyme is encoded by a single mRNA as a single polypeptide that is posttranslationally processed to generate the subunits and is glycosylated. After preparing first-strand cDNA from leukocyte and fibroblast total RNA, we used the polymerase chain reaction to amplify the glycoasparaginase cDNA of eight Finnish aspartylglycosaminuria patients. We demonstrate that the Finnish patients' mRNA sequence differed from the normal sequence by two single-base changes six nucleotides apart from one another in the heavy chain of glycoasparaginase. The first change resulted in the replacement of arginine by glutamine (R161Q), whereas the second change resulted in a cysteine to serine substitution (C163S). Both mutations resulted in novel restriction endonuclease sites and were present in all eight Finnish aspartylglycosaminuria patients originating from different pedigrees, but they were absent from Finnish and non-Finnish controls and a non-Finnish case of aspartylglycosaminuria. These results indicate molecular homogeneity in aspartylglycosaminuria alleles in the Finnish population.

Amino Acid Sequence↗
PubMed1991

Glycosaparaginase from human leukocytes. Inactivation and covalent modification with diazo-oxonorvaline.

The apparent active site of human leukocyte glycoasparaginase (N4-(beta-acetylglucosaminyl)-L-asparaginase EC 3.5.1.26) has been studied by labeling with an asparagine analogue, 5-diazo-4-oxo-L-norvaline. Glycoasparaginase was purified 4,600-fold from human leukocytes with an overall recovery of 12%. The purified enzyme has a Km of 110 microM, a Vmax of 34 mumol x l-1 x min-1, and a specific activity of 2.2 units/mg protein with N4-(beta-N-acetylglucosaminyl)-L-asparagine as substrate. The carbohydrate content of the enzyme is 15%, and it exhibits a broad pH maximum between 7 and 9. The 88-kDa native enzyme is composed of 19-kDa light (L) chains and 25-kDa heavy (H) chains and it has a heterotetrameric structure of L2H2-type. The glycoasparaginase activity decreases rapidly and irreversibly in the presence of 5-diazo-4-oxo-L-norvaline. At any one concentration of the compound, the inactivation of the enzyme is pseudo-first-order with time. The inhibitory constant, K1, is 80 microM and the second-order rate constant 1.25 x 10(3) M-1 min-1 at pH 7.5. The enzyme activity is competitively protected against this inactivation by its natural substrate, aspartylglucosamine, indicating that this inhibitor binds to the active site or very close to it. The covalent incorporation of [5-14C]diazo-4-oxo-L-norvaline paralleled the loss of the enzymatic activity and one inhibitor binding site was localized to each L-subunit of the heterotetrameric enzyme. Four peptides with the radioactive label were generated, purified by high performance liquid chromatography, and sequenced by Edman degradation. The sequences were overlapping and all contained the amino-terminal tripeptide of the L-chain. By mass spectrometry, the reacting group of 5-diazo-4-oxo-L-norvaline was characterized as 4-oxo-L-norvaline that was bound through an alpha-ketone ether linkage to the hydroxyl group of the amino-terminal amino acid threonine.

Amino Acid Sequence↗
PubMed1991

Estimating the risk of a fetal autosomal trisomy at mid-trimester using maternal serum alpha-fetoprotein and age: a retrospective study of 142 pregnancies.

Risks appropriate for mid-trimester prenatal screening for autosomal trisomies have been estimated from a combination of maternal age and maternal serum (MS) alpha-fetoprotein (AFP) levels at 16-20 weeks gestation. Published data on the frequency of Down's syndrome births relative to maternal age were modified to include the additional age-related frequency of trisomy 18 and trisomy 13 cases to provide an overall risk for an autosomal trisomy at mid-trimester. MSAFP results from a retrospective study of 142 affected (114 trisomy 21, 19 trisomy 18, and 9 trisomy 13) and 113,000 unaffected pregnancies were converted to multiples of the appropriate gestational median (MOM). The AFP levels in the autosomal trisomy pregnancies were found to be significantly reduced at 0.72 MOM of the unaffected pregnancies. Risks (likelihood ratios) were derived from the overlapping log Gaussian distributions for affected and unaffected pregnancies and combined with maternal age risks to give the overall odds of an affected pregnancy. A mid-trimester cut-off risk of 1:280 gave an estimated 37 per cent detection rate for autosomal trisomies in the west of Scotland population for a follow-up (false-positive) rate of 6.6 per cent. These figures compare with a 30 per cent detection and 6.7 per cent false-positive rate if age 35 years and over is used as the sole criterion for selection of at-risk pregnancies.

Adolescent↗
PubMed1991

Mapping of the von Hippel-Lindau disease locus to a small region of chromosome 3p by genetic linkage analysis.

Genetic linkage studies were performed in 22 families with von Hippel-Lindau (VHL) disease by using polymorphic DNA markers from distal chromosome 3p. Linkage was detected between VHL disease and the markers D3S18 (Zmax = 6.6 at theta = 0.0, confidence interval (CI) 0.00-0.06), RAF1 (Zmax = 5.9 at theta = 0.06, CI 0.01-0.16), and THRB (Zmax 3.4 at theta = 0.11). Multipoint linkage analysis localized the VHL disease gene within a small region (approximately 8 cM) of 3p25-p26 between RAF1 and (D3S191, D3S225) and close to the D3S18 locus. There was no evidence of locus heterogeneity, and families with and without pheochromocytoma showed linkage to D3S18. The identification of DNA markers flanking the VHL disease gene allows reliable presymptomatic and prenatal diagnosis to be offered to informative families.

Adrenal Gland Neoplasms↗
PubMed1991

Familial renal cell carcinoma: clinical and molecular genetic aspects.

Renal cell carcinoma (RCC) accounts for 2% of all human cancer, but familial cases are infrequent. Riches (1963) and Griffin et al. (1984) in a population-based case-control study found a family history of renal cell carcinoma in 2.4% of affected patients compared to 1.4% of controls. Nevertheless the importance of inherited tumours in clinical practice and medical research is disproportionate to their frequency. In clinical practice recognition of familial RCC can provide opportunities to prevent morbidity and mortality by appropriate screening. In medical research recent advances in molecular genetics offer the prospect of isolating the genes involved in the pathogenesis of familial RCC and of the more common sporadic cases. In this article we review the clinical and molecular genetics of inherited renal cell carcinoma (adenocarcinoma or hypernephroma).

Carcinoma, Renal Cell↗
PubMed1991

Von Hippel-Lindau disease: a genetic study.

Genetic aspects of von Hippel-Lindau (VHL) disease were studied in familial and isolated cases. Complex segregation analysis with pointers was performed in 38 kindreds with two or more affected members. Dominant inheritance with almost complete penetrance in the highest age classes (0.96 at 51 to 60 and 0.99 at 61 to 70 years) was confirmed and there was no evidence of heterogeneity between families ascertained through complete and incomplete selection. The point prevalence of heterozygotes in East Anglia was 1.89/100,000 (1/53,000) persons with an estimated birth incidence of 2.73/100,000 (1/36,000) live births. Reproductive fitness was 0.83. Direct and indirect estimates of the mutation rate were 4.4 (95% CI 0.9 to 7.9) x 10(-6)/gene/generation and 2.32 x 10(-6)/gene/generation respectively. There was no significant association between parental age or birth order and new mutations for VHL disease.

Adult↗
PubMed1990

Physical mapping of deletion breakpoints in patients with X-linked ichthyosis: evidence for clustering of distal and proximal breakpoints.

Previous studies have shown that approximately 80% of patients with X-linked ichthyosis have a total deletion of the steroid sulphatase (STS) locus which lies in Xp22.3-Xpter. We show by Southern analysis that a common core of sequences are absent in 78.6% of our cases, suggesting that the deletion breakpoints may be highly clustered. To characterize the region in more detail a long-range physical map of over 3 megabases (Mb) surrounding the STS locus was constructed using pulse-field gel electrophoresis. The map enabled the order of sequences tel-SI19-GMGXY3-[STS,GMGXY19]-GMGX9-[dic56 ,SIII2]-cen and the localization of the deletion breakpoints to be established. In ten cases the pulse-field evidence supports the clustering of breakpoints and indicates a deletion size of 2 Mb in most patients. Five CpG islands have been positioned around the STS locus and may be associated with other loci in the region involved in mental retardation and Kallman's syndrome. The map will be instrumental in an attempt to isolate and characterize the deletion breakpoints and to access other genes located in the region.

Arylsulfatases↗
PubMed1990

The amino acid sequence of the acidic subunit B-chain of crotoxin.

The B-chain of the acidic subunit of crotoxin proved refractory to Edman degradation. When subjected to sequence analysis using tandem mass spectrometry, pyroglutamate was found at the amino-terminal end, even though earlier attempts to de-block with pyroglutamate aminopeptidase were unsuccessful. The B-chain contained 35 amino acids and showed 91% amino acid identity with the corresponding segment from Mojave toxin, a homologous neurotoxin from Crotalus scutulatus scutulatus. The sequence of the last 24 residues of the B-chain is consistent with that previously published (Aird, S.D., Kaiser, I.I., Lewis, R.V. and Kruggel, W.G. (1985) Biochemistry 24, 7054-7058), except at position 20, where Edman degradation gave glycine and mass spectrometry gave glutamic acid.

Amino Acid Sequence↗
PubMed1990

Metabolism-based covalent bonding of the heme prosthetic group to its apoprotein during the reductive debromination of BrCCl3 by myoglobin.

The reductive metabolism of BrCCl3 by ferrous myoglobin leads to the alteration of the prosthetic heme to form products that can be dissociated from the protein and to those that are irreversibly bound to the protein. The major dissociable or soluble heme metabolites have recently been characterized. In this study, the irreversibly bound heme product was characterized by Edman degradation, amino acid analysis, and electronic absorption and mass spectrometry of peptides derived from the altered protein. It was found that the prosthetic heme was modified by a CCl2 moiety derived from BrCCl3 and was covalently bound to histidine residue 93, the normal proximal ligand to the heme-iron. The data are consistent with a mechanism by which the trichloromethyl radical reacts with the heme to form an intermediate that either can alkylate the proximal histidine residue or form soluble metabolites. The covalent bonding of the heme prosthetic moiety to the apoprotein likely leads to a change in the tertiary structure of the protein that may be responsible for its altered catalytic activity as well as its enhanced susceptibility to proteolysis. Similar processes may account, at least in part, for the covalent alteration of the heme prosthetic group of other hemoproteins caused by xenobiotics and endogenous substrates.

Amino Acid Sequence↗
PubMed1990

The complete sequence of the acidic subunit from Mojave toxin determined by Edman degradation and mass spectrometry.

Mojave toxin, a heterodimeric, neurotoxic phospholipase complex from Crotalus scutulatus scutulatus, is one of a group of closely related rattlesnake toxins for which much structural information is still lacking. The complete amino-acid sequence of the acidic subunit from Mojave toxin was determined. The three individual peptide chains, derived from the acidic subunit by reductive alkylation, were separated by high-performance liquid chromatography. Fragmentations of the A and B chains were done using specific proteinases and the resulting peptide mixtures were fractionated by reverse-phase high-performance liquid chromatography. Sequence analyses on the intact chains and the fragments from digests were done by automated Edman degradation, carboxypeptidase Y degradation and triple-quadrupole and tandem-quadrupole Fourier-transform mass spectrometry. The sequence for each acidic subunit chain is very similar to the corresponding chain from the related neurotoxin complex, crotoxin, and overall the sequence is similar to the sequences of group I and II phospholipases A2. The N-terminus of the B chain is blocked by pyroglutamic acid. The existence of two distinct and closely related C chains was established. It is unlikely that the small sequence difference can account for the isoforms that are present in purified Mojave toxin and in unfractionated venom.

Amino Acid Sequence↗
PubMed1990

Mapping of von Hippel-Lindau disease to chromosome 3p confirmed by genetic linkage analysis.

Genetic linkage studies were performed in 12 British families with von Hippel-Lindau disease (VHL) using RFLPs at three loci (DNF15S2, THRB, RAF1) on the short arm of chromosome 3. Linkage was detected between the VHL disease locus and RAF1 with a maximum lod score of 3.88 at a recombination fraction of 0.05 (confidence interval 0.003-0.18). Multipoint linkage analysis suggested that the most likely location for the VHL disease locus is telomeric to THRB. These results confirm earlier reports localizing the VHL gene to the short arm of chromosome 3, and provide no evidence for genetic heterogeneity.

Chromosome Mapping↗