Disease relevance of SNTB1

• Brazilian family with pure autosomal dominant spastic paraplegia maps to 8q: analysis of muscle beta 1 syntrophin [1].
• Analyses of beta-1 syntrophin, syndecan 2 and gem GTPase as candidates for chicken muscular dystrophy [2].
• A statistically significant difference did emerge when the A+AB excess in thrombosis was contrasted with the O+B excess in haemorrhage, suggesting that this difference might be accounted for the major A subgroup (A1) and, consequently, A1B [3].
• The recombinant A1B protein, expressed in Escherichia coli, shows the same electrophoretic mobility and charge as the cellular one [4].
• Chromatographic evidence indicated that the three trisaccharide structures were also present in other A1, A2, A1B and A2B ovarian cyst glycoproteins and in A1 and A2 salivary glycoproteins [5].

High impact information on SNTB1

• We expressed the cDNA of human beta 1-syntrophin and the COOH terminus of human dystrophin in reticulocyte lysates using an in vitro transcription/translation system [6].
• The C-terminal Gly-rich domain is necessary for alternative splicing activity, for stable RNA binding and for optimal RNA annealing activity. hnRNP A1B, which is an alternatively spliced isoform of hnRNP A1 with a longer Gly-rich domain, binds more strongly to pre-mRNA but has only limited alternative splicing activity [7].
• In vitro translation of the mRNAs selected by hybridization with A1 cDNA produced two proteins of 34 and 38 kd; Northern blot analysis of poly(A)+ RNA from HeLa cells revealed that the abundance of the A1B mRNA was approximately 5% that of A1 [4].
• At 2030 in an A1B future, increased O(3) precursor emissions enhance surface sulfate over India and China by up to 20% because of increased levels of OH and gas-phase SO(2) oxidation rates and add up to 20% to the direct sulfate forcing for that region relative to the present day [8].
• A comparison of our human cDNA sequence with the GenBank expressed sequence tag (EST) data base has identified a relative from human skeletal muscle, EST25263, which is probably a human homologue of the published mouse syntrophin 2 [9].

Biological context of SNTB1

• Orthologues of SNTB1, SDC2 and GEM were syntenic to human chromosome 8q [2].
• Upregulation of beta1-syntrophin in neuromuscular disorders is associated with re-expression of the fetal nicotinic acetylcholine receptor gamma-subunit, cardiac actin, and neonatal myosin, suggesting reversion of muscle fibers to an immature phenotype [10].
• Small interference RNA inhibition of beta1-syntrophin expression reduced cholesterol efflux from primary skin fibroblasts by 50% while decreasing efflux 30% in bone marrow-derived macrophages [11].
• In the heterogeneous nuclear ribonucleoprotein (hnRNP) A1 pre-mRNA, different regions in the introns flanking alternative exon 7B have been implicated in the production of the A1 and A1B mRNA splice isoforms [12].
• We report that SF2/ASF levels were substantially increased in the lower uterine region, and this was associated with a parallel decrease in levels of hnRNP A1/A1B during gestation [13].

Anatomical context of SNTB1

• A novel interaction with the PDZ protein beta1-syntrophin was identified using this approach, and this interaction was confirmed in human THP-1 macrophages and in mouse liver [11].
• Affinity-purified antibodies against rabbit 59-1 DAP fusion proteins only recognize the lowest band of the 59-DAP triplet in skeletal muscle sarcolemma and isolated dystrophin-glycoprotein complex [14].
• We conclude that biglycan is important for the maintenance of muscle cell integrity and plays a direct role in regulating the expression and sarcolemmal localization of the intracellular signaling proteins dystrobrevin-1 and -2, alpha- and beta1-syntrophin and nNOS [15].
• The existence of atypical blood group galactosyltransferase which causes an expression of A2 character in A1B red blood cells [16].
• Spatio-temporal expression of the trans-acting splicing factors SF2/ASF and heterogeneous ribonuclear proteins A1/A1B in the myometrium of the pregnant human uterus: a molecular mechanism for regulating regional protein isoform expression in vivo [13].

Associations of SNTB1 with chemical compounds

• Aminoisobutyric acid (A1B), a specific substrate of the A system of amino acid transport, at a concentration between 1 and 50 mM had no significant effect on melphalan uptake at 3 min in any of the human cells studied except those of patient C [17].
• Alpha 1-beta glycoprotein (A1B) was purified to homogeneity from human plasma using a three-step procedure involving pseudo-ligand affinity chromatography on immobilized Cibacron Blue 3-GA, gel filtration chromatography on Sephadex G-200 and ion-exchange chromatography on DEAE Affigel Blue. The overall yield of the combined techniques was 31% [18].
• Normal human erythrocytes of blood groups A1, A2, B and O, and En (a-) erythrocytes lacking glycophorin A, but with A1B-activity, were surface-labeled with tritiated sodium borohydride after oxidation of terminal galactosyl and N-acetylgalactosaminyl residues with galactose oxidase [19].

Physical interactions of SNTB1

• Mammalian alpha 1- and beta 1-syntrophin bind to the alternative splice-prone region of the dystrophin COOH terminus [20].

Analytical, diagnostic and therapeutic context of SNTB1

• Immunohistochemical and Western Blot (WB) studies showed that the distribution, expression, and apparent molecular weight of the beta 1 syntrophin protein were comparable to those of normal control individuals [1].
• ABO-incompatible kidney transplantation of an 8-yr-old girl with donor/recipient-constellation A1B/B [21].
• Protein content and enzymatic and allergenic properties of all venoms studied were determined by dye stain reagent, hyaluronidase and phospholipase A1B enzyme activities, and radioallergosorbent test inhibition studies, respectively [22].
• Several Black AB subjects classified as non-A1 by the agglutination test were identified as A1B and AintB on the enzyme basis [23].
• This case report describes the transplantation of a kidney from an A1B donor to a recipient who was blood group A2B [24].

References