Disease relevance of SAG

• Here, we have analyzed the T cell repertoire at the autoimmune site by examining V beta gene expression in the retinas of rats with SAg- or IRBP-induced uveitis [1].
• Experimental autoimmune uveoretinitis (EAU) is a T cell-mediated autoimmune disease that serves as a model of human intraocular inflammatory disease (uveitis) and is initiated in susceptible animals by immunization with retinal Ag, such as interphotoreceptor retinoid binding protein (IRBP) and S-Ag (SAg) [1].
• Pineal parenchymal tumors demonstrate a highly variable and incomplete photosensory differentiation evidenced by specific cytoarchitectural features and the expression of photosensory retinal S-Antigen (S-Ag) [2].
• Cell-mediated immune responses to human retinal S-antigen, interphotoreceptor retinoid binding protein (IRBP), and crude retinal extract were investigated in patients with onchocerciasis from Sierra Leone, West Africa using a two-step migration-inhibition factor assay [3].
• Using analytical flow cytometry, we show that recombinant human IFN-gamma can enhance the expression of retinal S-antigen in retinoblastoma cells [4].

Psychiatry related information on SAG

• As a group, the anti-68/48 kDa-positive CFS patients presented more frequently with hypersomnia (P<0.005), short-term amnesia (P<0.07) or difficulty in concentration (P<0.05) than those CFS patients without the antibodies [5].

High impact information on SAG

• Peripheral blood lymphocytes from the seven cyclosporin A responsive patients, but not those from the non-responder, gave positive in-vitro blastogenic responses to the retinal S-antigen, a highly uveitogenic organ-specific material [6].
• PIDD (p53-induced protein with a death domain) is constitutively processed giving rise to a 48-kDa N-terminal fragment containing the leucine-rich repeats (LRRs, PIDD-N) and a 51-kDa C-terminal fragment containing the death domain (DD, PIDD-C) [7].
• In addition to MHC class I and II antigens, intestinal epithelia constitutively express the nonclassical MHC molecule CD1d, a transmembrane molecule with a short cytoplasmic tail expressed as a beta(2)-microglobulin-associated 48-kDa glycoprotein and novel beta(2)-microglobulin-independent 37-kDa nonglycosylated protein on intestinal epithelia [8].
• In response to wounding, a 48-kDa myelin basic protein (MBP) kinase is activated within 2 min, both locally and systemically, in leaves of young tomato plants [9].
• In def1, a mutant tomato line having a defective octadecanoid pathway, the 48-kDa MBP kinase is activated by wounding and systemin as in the wild-type plants [9].

Chemical compound and disease context of SAG

• Cellular immune response to retinal S-antigen & interphotoreceptor retinoid binding protein fragments in idiopathic human uveitis [10].
• The human cytomegalovirus UL4 gene encodes a 48-kDa glycoprotein, expression of which is repressed at the translational level by a short upstream open reading frame (uORF2) within the UL4 transcript leader [11].
• We developed a solid-phase two-site immunoenzymometric assay (IEMA) of the estrogen-induced 52-kDa cathepsin D (EC 3.4.23.5) and its processed forms (48-kDa and 34-kDa proteins) in cytosols of breast cancer tissues, using two monoclonal antibodies directed against two different epitopes of these antigens [12].
• Antibodies raised against the 48-kDa subunit showed cross-reactions with extracts of E. acidaminophilum grown on different substrates and with extracts from other glycine-utilizing anaerobic bacteria such as Clostridium purinolyticum, C. sticklandii, and C. sporogenes [13].
• Using a photoaffinity analogue of methotrexate, we have identified the involvement of a 48 kDa membrane protein and a 38 kDa cytosolic or peripheral membrane protein in the transport of this compound into murine L1210 leukemia cells [14].

Biological context of SAG

• The complete amino acid sequence of human retinal S-antigen (48 kDa protein), a retinal protein involved in the visual process has been determined by cDNA sequencing [15].
• DNA sequence analysis of 75 V beta 8 cDNA clones from uveitogenic T cell lines revealed that, of 20 V beta 8 clones isolated from SAg-specific T cell lines, all were V beta 8.2 TCR, whereas among 55 V beta 8 clones from IRBP-specific lines, 36 were V beta 8.2 and 19 were V beta 8 [1].
• In isolated blowfly rhabdoms photoconversion of P to M affects bacterial toxin-catalyzed ADP-ribosylation of a 41-kDa protein, activates phosphorylation of opsin and induces the binding of a 48-kDa phosphoprotein to the rhabdomeric membrane [16].
• Autoimmune responses toward retinal S antigen are often observed in patients with retinal inflammatory disease, however, these responses are usually secondary to local tissue damage [17].
• We previously purified a 48-kDa protein (p48) that specifically reacts with an antiserum directed against the 12 carboxyl-terminal amino acids of the c-myc gene product [18].

Anatomical context of SAG

• Our data show the following: 1) T cell response to SAg or IRBP is clonally heterogeneous: at least 15 of the 20 known rat TCR families were detected in the retinas of rats with EAU [1].
• Low molecular mass phosphoproteins from the frog rod outer segments form a complex with 48 kDa protein [19].
• Retinal S antigen is a soluble protein found in abundance in photoreceptor cells [17].
• Protein patterns obtained by sodium dodecyl sulfate gel electrophoresis of irradiated retina membranes show an increased incorporation of label from [gamma-32P]ATP also into protein bands of 48 kDa, 68 kDa and 200 kDa [16].
• Immunoaffinity-purified human antipeptide IgA antibodies detected HPV-specific 58- and 48-kDa proteins in cervical carcinoma cell extracts and also detected a nuclear antigen in HPV-carrying cervical cancer cell lines and cervical intraepithelial neoplasia biopsied tissue [20].

Associations of SAG with chemical compounds

• Cellular immune response to retinal S-antigen and interphotoreceptor retinoid-binding protein fragments in Eales' disease patients [21].
• A 48-kDa MBP kinase is also activated by the 18-amino acid polypeptide systemin, a potent wound signal for the synthesis of systemic wound response proteins (swrps) [9].
• A 48-kDa MBP kinase activity also increases in response to polygalacturonic acid and chitosan but not in response to jasmonic acid or phytodienoic acid [9].
• The human protein tyrosine phosphatase TCPTP exists as two forms: an endoplasmic reticulum-targeted 48-kDa form (TC48) and a nuclear 45-kDa form (TC45) [22].
• At 30 sec after glutamate stimulation, 32P incorporation into the 87-kDa and 48-kDa proteins peaked (240% and 170% basal levels, respectively), and by 2 min, phosphorylation of the 87-kDa protein had returned to basal levels, while that of the 48-kDa protein decreased but remained above control levels [23].

Physical interactions of SAG

• Retinal S-antigen (SAg) and interphotoreceptor retinol-binding protein (IRBP) induced experimental autoimmune uveitis (EAU) and experimental autoimmune pinealitis (EAP) are good models for studying the mechanisms involved in autoimmune diseases [24].
• We have identified a human gene encoding a 48-kDa protein that specifically interacts with the peptidyl prolyl isomerase FK506-binding protein 59 (FKBP59) and also with the well known FKBP12 [25].
• ISGF3 gamma DNA-binding activity was identified as a 48-kDa polypeptide, and partial amino acid sequence has allowed isolation of cDNA clones [26].
• Unlike 125I-Lys-plasmin, the 48-kDa fragment did not form a complex with alpha 2 plasmin inhibitor [27].
• We have recently shown that the domain of von Willebrand factor (vWF) which interacts with the platelet glycoprotein Ib (GPIb) is located in a 52/48-kDa tryptic fragment of the molecule which begins with amino acid residue Val-449 [28].

Enzymatic interactions of SAG

• Here, we demonstrate that human RAD21 is preferentially cleaved at Asp(279) by caspases-3 and -7 in vitro to generate two major proteolytic products of approximately 65 and 48 kDa [29].
• Additional 63- and 48-kDa phosphorylated fragments are generated upon trypsin treatment of EGF receptor from EGF-treated cells [30].

Regulatory relationships of SAG

• Photoaffinity labeling of CCR1 and CCR5 receptors stably expressed in CHO cells resulted in specific covalent attachment of [(125)I]BP-MIP-1alpha and production of protein complexes of 54 and 48 kDa, respectively, on SDS-PAGE [31].
• Fifteen monoclonal antibodies against the 52/48-kDa fragment inhibited von Willebrand factor binding to collagen [32].

Other interactions of SAG

• Divergence in amino acid sequence at the carboxyl terminus of S-antigen (rod photoreceptor arrestin) and beta-arrestin 1 and beta-arrestin 2 (beta-adrenergic receptors) suggests that receptor specificity may be coded within this region [33].
• Functional desensitization of the isolated beta-adrenergic receptor by the beta-adrenergic receptor kinase: potential role of an analog of the retinal protein arrestin (48-kDa protein) [34].
• Inactivation of photoexcited rhodopsin in retinal rods: the roles of rhodopsin kinase and 48-kDa protein (arrestin) [35].
• Tyrosine-phosphorylated Stat1 and Stat2 plus a 48-kDa protein all contact DNA in forming interferon-stimulated-gene factor 3 [36].
• The 84-, 91-, and 113-kDa proteins of the ISGF-3 alpha complex are phosphorylated on tyrosine residues upon alpha interferon (IFN-alpha) treatment and subsequently translocate to the nucleus together with a 48-kDa subunit [37].

Analytical, diagnostic and therapeutic context of SAG

• 5. The elution profile of Components I and II upon gel-chromatography and ion-exchange chromatography coincides with that of major rod outer segment 48 kDa protein [19].
• These antibodies precipitate a 90-nucleotide RNA from human whole cell extracts and recognize a 48-kDa polypeptide in immunoblotting assays [38].
• We establish that two FLI-1 protein isoforms (of 51 and 48 kDa) detected by Western blotting in vivo are synthesized by alternative translation initiation through the use of two highly conserved in-frame initiation codons, AUG +1 and AUG +100 [39].
• Immunoprecipitation of activated caspase-3 from radiolabeled virus-infected cells revealed the co-precipitation of a 48-kDa protein that was tentatively identified as viral protein 2BC [40].
• The approximately 48-kDa His-tag derivative proteins were purified by metal affinity chromatography, and their molecular and biochemical characteristics were studied [41].

References