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J C Hong

Publications and source records attributed to J C Hong.

At least 19 recordsLinked to original sources
PubMed2005

Correlation between cyclosporine-induced nephrotoxicity in reduced nephron mass and expression of kidney injury molecule-1 and aquaporin-2 gene.

Sirolimus (SRL) has been shown to exacerbate cyclosporine (CsA)-induced nephrotoxicity. The expression of the kidney injury molecule-1 (KIM-1) is markedly upregulated in the postischemic rat kidney. We sought to correlate drug-induced nephrotoxicity and the expression of KIM-1 and aquaporin-2 (AQP-2) in male PVG rats with 2 kidneys (2K), 1 kidney (1K), and half a kidney (1/2K) treated with SRL alone, CsA alone, or a combination of both (SRL-CsA). After 7 days of treatment, the 2K group treated with SRL-CsA showed a significant decrease in creatinine clearance compared with the 2K SRL alone and 2K CsA alone groups (1.2 vs 2.47 vs 2.46 mL/min; P < .001). There was a trend toward deterioration of creatinine clearance in the 1K and 1/2K groups treated with SRL-CsA. The KIM-1 expression in the 2K SRL-CsA group was significantly upregulated compared with that in the 2K SRL alone and 2K CsA alone groups (P = .02). The AQP-2 expression was comparable in the 3 groups. After 1 week of treatment washout, the 2K, 1K, and 1/2K groups treated with SRL alone demonstrated a significantly higher creatinine clearance rate than did the groups treated with SRL-CsA (P = .04, P = .02, and P = .004). The expression of KIM-1 and AQP-2 was similar among the treatment groups. SRL-CsA-induced nephrotoxicity resulted in overexpression of KIM-1, suggesting injury to the proximal tubule. Treatment with SRL alone may enable earlier reversal of tubular injury.

Animals↗
PubMed2001

Sirolimus rescue therapy for refractory rejection in renal transplantation.

BACKGROUND: Acute renal allograft rejection episodes refractory to antilymphocyte preparations almost inevitably progress to transplantation loss. To reverse ongoing rejection processes, we administered sirolimus (RAPA) after failure of conventional immunosuppressive regimens including full courses of antilymphocyte sera. METHODS: All 36 renal transplantation recipients reported herein displayed either Grade IIB or Grade III biopsy-proven (Banff 1993 criteria) ongoing rejection episodes despite prior treatment with pulse and/or oral recycling of steroids and at least one 14- to 21-day course of murine (OKT3) or equine (ATGAM) antilymphocyte treatment. We compared the actual 12-month outcomes of two demographically similar cohorts of patients treated for refractory rejection with RAPA (Group I; n=24) or mycophenolate mofetil (MMF; Group II; n=12) added to a baseline regimen of cyclosporine (CsA)/prednisone (Pred). RESULTS: Rescue therapy reversed the renal dysfunction in 96% of patients in the RAPA group versus 67% in the MMF group (P=0.03) despite the fact that a greater fraction of patients in the RAPA (17 of 24) than the MMF group (6 of 12) had experienced two or more episodes of acute rejection before study entry and the fact that the recurrent bouts of acute rejection occurred within the first 6 months posttransplant in 94% of patients in the RAPA group compared with 50% (P=0.005) in the MMF group. Among the patients who were reversed successfully, the rates of rebound acute rejection were similar (4% vs. 8%). The mean serum creatinine values were slightly, although not significantly, lower among RAPA than MMF patients at 1, 3, 6, and 12 months: namely, 2.6 vs. 2.8, 2.8 vs. 3.2, 3.0 vs. 3.3, and 2.8 vs. 3.2 mg/dL, respectively. The 1-year patient and graft survival rates were similar: namely, 88% vs. 92% and 83% vs. 67% for the RAPA versus MMF groups. CONCLUSION: RAPA is a potent immunosuppressive agent for the treatment of refractory renal allograft rejection.

Adult↗
PubMed2001

A calcineurin antagonist-free induction strategy for immunosuppression in cadaveric kidney transplant recipients at risk for delayed graft function.

BACKGROUND: Avoidance of calcineurin antagonists for a prolonged period de novo after cadaver donor renal transplantation may facilitate recovery from delayed graft function. The present study examined the benefit of prolonging the calcineurin antagonist-free interval by administering sirolimus (SRL) in combination with chimeric (c-) anti-interleukin-2 receptor (IL-2R) monoclonal antibodies (mAb). METHODS: Three contemporaneous but nonrandomized cohorts were compared for acute rejection episodes, patient and graft survival rates, renal function, and adverse reaction profiles for 12 months. Patients with delayed graft function were treated with either SRL/c-IL-2R mAb/prednisone (Pred) with inception of cyclosporine (CsA) once the serum creatinine value was < or =2.5 mg/dl (n=43; group 1) or anti-lymphocyte preparations/Pred/delayed CsA for 7 to 14 days (n=18; group 3). A third cohort displayed immediate function and was treated de novo with CsA/c-IL-2R mAb/Pred (n=21; group 2). RESULTS: The incidence of acute rejection episodes was significantly lower among group 1 (16%) compared with groups 2 (52%, P=0.004) or 3 (39%, P=0.05). Among the seven rejection episodes in group 1, six of seven occurred among African-American or retransplant recipients, and a separate cluster of six of seven occurred among patients who displayed SRL trough concentrations < or =9 ng/ml. Furthermore, additional antilymphocyte antibody treatment was required to reverse either steroid-resistant or Banff grades II or III acute rejection episodes among 14%, 55% (P=0.08), and 71% (P=0.03) of patients in each group, respectively. Patient and graft survival rates, as well as mean serum creatinine values, were similar at 12 months among the three groups. However, group 1 patients displayed higher serum cholesterol and triglyceride values, as well as lower hemoglobin, platelet, and leukocyte values compared with the other two groups. CONCLUSION: This pilot study suggests that a SRL/c-IL-2R mAb/Pred induction regimen provides excellent acute rejection prophylaxis.

Antibodies, Monoclonal↗
PubMed2001

Evaluation of premalignant potential in oral lichen planus using interphase cytogenetics.

This study attempted to evaluate whether oral lichen planus (OLP) has the potential to progress to oral squamous cell carcinoma (OSCC) by comparing the degree of genetic instability between clinically-curable OLP and lesions that progressed to OSCC. Fifteen cases of steroid-responsive OLP and two cases of lichenoid dysplasia (LD) that progressed to OSCC were used for this study. Chromosome in situ hybridization (CISH) was performed for chromosomes 9 and 17. The fraction of polysomic and monosomic cells for chromosome 9 increased in mucosal epithelium compared to those of lymphocytes in OLP. This difference was statistically significant (P=0.0017, 0.0054, respectively). Two LD patients showed 15.38% and 22.58% of PI for chromosome 9. In OSCC that developed from LD, the fraction of monosomic cells for chromosome 9 increased by more than 70%. We concluded that LD should be treated as a high-risk premalignant lesion and strongly suggest that the monosomy of chromosome 9 may have a critical role in progress to malignancy from LD.

Adult↗
PubMed2001

A novel cold-inducible zinc finger protein from soybean, SCOF-1, enhances cold tolerance in transgenic plants.

Cold stress on plants induces changes in the transcription of cold response genes. A cDNA clone encoding C2H2-type zinc finger protein, SCOF-1, was isolated from soybean. The transcription of SCOF-1 is specifically induced by low temperature and abscisic acid (ABA) but not by dehydration or high salinity. Constitutive overexpression of SCOF-1 induced cold-regulated (COR) gene expression and enhanced cold tolerance of non-acclimated transgenic Arabidopsis and tobacco plants. SCOF-1 localized to the nucleus but did not bind directly to either C-repeat/dehydration (CRT/DRE) or ABA responsive element (ABRE), cis-acting DNA regulatory elements present in COR gene promoters. However, SCOF-1 greatly enhanced the DNA binding activity of SGBF-1, a soybean G-box binding bZIP transcription factor, to ABRE in vitro. SCOF-1 also interacted with SGBF-1 in a yeast two-hybrid system. The SGBF-1 transactivated the beta-glucuronidase reporter gene driven by the ABRE element in Arabidopsis leaf protoplasts. Furthermore, the SCOF-1 enhanced ABRE-dependent gene expression mediated by SGBF-1. These results suggest that SCOF-1 may function as a positive regulator of COR gene expression mediated by ABRE via protein-protein interaction, which in turn enhances cold tolerance of plants.

Abscisic Acid↗
PubMed2000

Sirolimus-induced thrombocytopenia and leukopenia in renal transplant recipients: risk factors, incidence, progression, and management.

BACKGROUND: Our study assessed the factors that predispose renal transplant recipients to the occurrence of thrombocytopenia and leukopenia, as well as the severity and the time- and concentration-dependence of these side-effects, after administration of sirolimus (SRL) in combination with a cyclosporine (CsA) and prednisone (Pred) regimen. METHODS: The clinical courses of two cohorts of renal transplant recipients were compared over 1 year: 119 patients received SRL in addition to CsA and Pred, and 65 demographically similar, concurrent patients received only CsA and Pred. Using an analysis of variance, pretransplant laboratory values and SRL trough concentrations (C0) were correlated with the occurrence, severity, and persistence of drug-induced thrombocytopenia (platelet count <150x10(3) cell/mm3) and/or leukopenia (white blood cell count <5,000/mm3). RESULTS: Neither the ethnic background nor the pretransplant cytomegalovirus serological status was associated with the occurrence of hematological complications. Thrombocytopenia was usually observed during the first 4 weeks of treatment (P=0.004). The occurrence, but not the severity or the persistence, of both thrombocytopenia and leukopenia correlated significantly with SRL trough concentrations > or =16 ng/ml (P=0.001 and 0.0001, respectively). A significant correlation is evident between the occurrence of the two adverse effects (P=0.001). In 89% of patients, the first episode of either type of cytopenia resolved spontaneously. Among the remaining 11%, 7% responded to SRL dose reduction, and 4% to temporary suspension. No patient required permanent cessation of SRL therapy. Most patients experienced repeated, but self-limited, episodes of toxicity. CONCLUSION: Thrombocytopenia and leukopenia are not infrequent occurrences with SRL treatment, and they generally resolve spontaneously.

Adolescent↗
PubMed2000

Alkali-catalyzed beta-elimination of periodate-oxidized glycans: a novel method of chemical deglycosylation of mucin gene products in paraffin embedded sections.

Altered expression of mucin gene products has been described in many epithelial cancers including colorectal cancer. However, mucins are heavily O-glycosylated making the study of apomucin expression difficult. In this study, we describe a novel method of chemical deglycosylation of mucin gene products on paraffin embedded formalin-fixed tissue sections. In the normal and cancerous colorectum, our results suggest that alkali-catalyzed beta-elimination of periodate oxidized glycan method of chemical deglycosylation modifies the structure of carbohydrates sensitive to mild periodate oxidation resulting in less steric hindrance and selectively removes Tn and sialyl-Tn structures, partially exposing the underlying apomucin epitopes. Using this method, we have demonstrated that the MUC1 tandem repeat epitope recognized by MAb 139H2 is masked predominantly due to steric hindrance by carbohydrate structures whereas the MUC2 tandem repeat epitope recognized by MAb CCP58 and pAb MRP and the MUC3 tandem repeat epitope recognized by pAb M3P are masked by the presence of carbohydrate side chains O-linked to Ser/Thr residues within the epitope. Considerable differences in the level and pattern of expression of the epitopes in the tandem repeat region of apomucins of MUC1, MUC2, and MUC3 were observed between normal and cancerous colorectal cancer tissues. We conclude that this novel chemical deglycosylation method that causes selective cleavage of distinct glycans will be useful in unmasking various mucin gene products and glycoproteins containing similar O-glycosidic linkages in the tissue sections of formalin-fixed paraffin embedded normal and pathological tissues.

Amino Acid Sequence↗
PubMed2000

Immunosuppressive agents in organ transplantation: past, present, and future.

The development of immunosuppressive agents reflects the progress in understanding the cellular and molecular mechanisms which mediate allograft rejection. Six paradigms represent the evolution of immunosuppressive strategies for organ transplantation. The proliferation paradigm advances agents which interrupt lymphocyte cell division (azathioprine, cyclophosphamide, mycophenolic acid). The depletion paradigm conscripts drugs that bind to lymphocyte cell surface markers, thereby producing cell lysis and/or inactivation (polyclonal ATGAM and thymoglobulin, and monoclonal OKT3 antilymphocyte antibodies). The cytokine paradigm uses agents that interrupt lymphocyte maturational events; eg, synthesis (calcineurin inhibitors: cyclosporine/tacrolimus), binding to surface receptors (anti-CD25 mAbs), or signal transduction phases of cytokine stimulation (sirolimus). The introduction of calcineurin inhibitors markedly reduces the rate of acute rejection episodes and increases short-term graft survival rates; nephrotoxicity and chronic allograft attrition remain as unanswered challenges. The cyclosporine A (CsA) sparing property of sirolimus permits the use of lower exposure to calcineurin agents, allows for early withdrawal of steroid therapy, and may delay allograft senescence. Furthermore, the combination of SRL with anti-IL-2R mAbs proffers an induction approach which allows prolonged periods of holiday from calcineurin inhibitors. To address the tissue nonselectivity of the calcineurin and mTOR inhibitors, which presumably causes the drug toxicities, new agents are being developed to selectively inhibit the T cell target Janus Kinase 3. In the costimulation paradigm, the accessory signals generated by antigen-presenting cells are interrupted by distinct agents: the receptor conjugate CTLA4-immunoglobulin and anti-B7 or anti-CD40 ligand mAbs. Another set of drugs (selectin blocking agents, anti-ICAM-1 antisense deoxy oligonucleotides, and the lymphocyte homing inhibitor FTY720) seeks to modulate the ischemia-reperfusion injury, which exacerbates cytokine-mediated events in the donor and the subsequent procurement injury and may also accelerate the progression of transplant senescence. Finally, the transplantation tolerance paradigm is based on the development of strategies which distort alloimmune recognition by antigen reactive cells (MHC peptides or proteins), produce anergy (costimulation blockers), functional inactivation, or deletion of antigen-reactive cells (donor bone marrow infusions and gene therapy). Presently, the optimal immunosuppressive strategy uses combinations of agents that act in synergistic fashion to provide the potency, freedom from toxic reactions, convenience of administration, and cost appropriate for the individual patient.

Animals↗
PubMed1999

Use of anti-CD25 monoclonal antibody in combination with rapamycin to eliminate cyclosporine treatment during the induction phase of immunosuppression.

BACKGROUND: Cyclosporine and tacrolimus are associated with drug-induced renal dysfunction that may exacerbate recovery from ischemic injuries during the first month posttransplant. We sought to use anti-CD25 (anti-interleukin-2 receptor) monoclonal antibodies in combination with sirolimus (rapamycin) to avoid cyclosporine therapy during the early postoperative period in six renal transplant recipients deemed to be at high risk for delayed graft function. METHODS: Six consecutive patients deemed to be at high risk for delayed graft function were treated with rapamycin (2-12 mg/day), anti-CD25 monoclonal antibodies, and steroids, withholding inception of cyclosporine therapy until the serum creatinine fell below 3.0 mg/dl. RESULTS: During the first 2 months posttransplant, none of the patients displayed clinical or histopathological evidence of acute allograft rejection episodes, cytokine release syndrome, or hypersensitivity reactions. None of the patients received even empiric bolus or high-dose steroid therapy for a presumed rejection episode. All patients recovered renal graft function within 8 weeks posttransplant. To date all patients have stable renal graft function. Five patients have serum creatinine levels between 0.8 to 1.3 mg/dl at 6 months and the other patient has a serum creatinine level of 1.7 mg/dl at present follow-up of 2 months posttransplant. CONCLUSION: During the early posttransplant period anti-CD25 monoclonal antibodies combined with rapamycin and steroids offer a promising baseline therapy to avoid cyclosporine exposure and facilitate recovery from ischemic/reperfusion injuries.

Adult↗
PubMed1999

Goblet cell-specific expression mediated by the MUC2 mucin gene promoter in the intestine of transgenic mice.

The regulation of MUC2, a major goblet cell mucin gene, was examined by constructing transgenic mice containing bases -2864 to +17 of the human MUC2 5'-flanking region fused into the 5'-untranslated region of a human growth hormone (hGH) reporter gene. Four of eight transgenic lines expressed reporter. hGH message expression was highest in the distal small intestine, with only one line expressing comparable levels in the colon. This contrasts with endogenous MUC2 expression, which is expressed at its highest levels in the colon. Immunohistochemical analysis indicated that goblet cell-specific expression of reporter begins deep in the crypts, as does endogenous MUC2 gene expression. These results indicate that the MUC2 5'-flanking sequence contains elements sufficient for the appropriate expression of MUC2 in small intestinal goblet cells. Conversely, elements located outside this region appear necessary for efficient colonic expression, implying that the two tissues utilize different regulatory elements. Thus many, but not all, of the elements necessary for MUC2 gene regulation reside between bases -2864 and +17 of the 5'-flanking region.

Animals↗
PubMed1998

Novel carbohydrate specificity of monoclonal antibody 91.9H prepared against human colonic sulfomucin: recognition of sulfo-Lewis(a) structure.

Monoclonal antibody (mAb) 91.9H was previously prepared against partially purified human colonic sulfomucins. The epitope was detected in normal colonic mucosa and primary and metastatic colorectal carcinoma in decreasing order of magnitude. In the present study, this antibody was shown to recognize sulfo-Le(a) structure, HSO3-3Gal beta 1-3(Fuc alpha 1-4)GlcNAc. Interactions between mAb 91.9H and synthetic oligosaccharides conjugated with biotinylated polyacrylamide carrier were examined by a biosensor based on surface plasmon resonance and by enzyme-linked immunosorbent assays. This mAb bound to sulfo-Lea but not to sulfo-LeX, Le(a), LeX, sialyl-Le(a), or sialyl-LeX. Sulfo-Le(a) oligosaccharides decreased its binding affinity with mAb 91.9H after periodate oxidation of its fucose residue. Immunohistochemical study showed a strong binding of mAb 91.9H to goblet cells in human colonic epithelia of Lewis-positive individuals but a trace binding in Lewis-negative individuals, confirming the specificity of this antibody toward structures containing a fucosylated type 1 backbone.

Antibodies, Monoclonal↗
PubMed1998

STF1 is a novel TGACG-binding factor with a zinc-finger motif and a bZIP domain which heterodimerizes with GBF proteins.

Two separate nuclear binding activities (B1 and B2) in the soybean apical hypocotyl have been identified that interact with a palindromic C-box sequence (TGACGTCA) and which are developmentally regulated in an inverse manner. The bZIP factors responsible for these two binding activities, B1 and B2, were isolated from a cDNA library and designated STGA1 and STFs (STF1 and STF2), respectively. Sequence analysis shows that the STFs contain both a zinc-finger domain and a bZIP domain. The two zinc finger sequences of Cys4-Cys4 are most related to the RING zinc-finger motif carrying a Cys3-His-Cys4. In addition the bZIP domain of STFs is highly homologous to the HY5 protein of Arabidopsis. DNA binding studies revealed that STF1 binding to the TGACGT sequence requires distinct flanking sequences. Furthermore, STF1 binds to the Hex sequence as a heterodimer with G-box binding factors (GBFs), a feature not observed with STGA1. Since STF1 expression is most prevalent in apical and elongating hypocotyls, it is proposed that STF1 may be a transcription factor involved in the process of hypocotyl elongation.

Amino Acid Sequence↗
PubMed1997

Differential expression of two functional serine/threonine protein kinases from soybean that have an unusual acidic domain at the carboxy terminus.

Two soybean cDNA clones, SPK-3 and SPK-4, encoding putative protein kinases were isolated and characterized. Both cDNAs encoded approximately 40-kDa serine/threonine kinases with unusual stretches of acidic amino acids in their carboxy-terminal regions, which are highly homologous to PKABA1 from wheat and ASKs from Arabidopsis. These kinases are encoded by one- or two-copy genes in the soybean genome. Notably, SPK-3 and -4 showed different patterns of expression in various soybean tissues. SPK-3 is highly expressed in dividing and elongating tissues of young seedlings but relatively weakly in tissues of mature plants. In contrast, SPK-4 showed relatively high and constitutive expression in all the tissues examined except for leaf tissues of mature plants. Although various stressors, such as dehydration and high salinity, increased the expression of both genes, the induction kinetics were different. The two genes also differed in their response to abscisic acid (ABA). SPK-3 was induced but SPK-4 was not affected by exogenously supplied abscisic acid. In accordance with these expression data analysis of the activity of a chimeric SPK-3 promoter::beta-glucuronidase (GUS) reporter gene by transient expression in tobacco leaves confirmed the inducibility of SPK-3 by salt and ABA. Polyclonal antibodies raised against a recombinant SPK-4 protein produced in Escherichia coli specifically recognized both recombinant SPK-3 and -4 proteins. Kinase assays using affinity-purified SPK-4/ antibody complexes with crude soybean extracts as substrate identified specific phosphorylation of two 41 and 170 kDa soybean proteins that were phosphorylated on serine residues. Taken together, our results suggest that SPK-3, and/or SPK-4 are functional serine protein kinase(s). Furthermore, SPK-3 and -4 may play different roles in the transduction of various environmental stresses.

Amino Acid Sequence↗
PubMed1995

Molecular cloning and functional characterization of a cDNA encoding nucleosome assembly protein 1 (NAP-1) from soybean.

NAP-1, a protein first isolated from mammalian cells, can introduce supercoils into relaxed circular DNA in the presence of purified core histones. Based on its in vitro activity, it has been suggested that NAP-1 may be involved in nucleosome assembly in vivo. We isolated a cDNA clone encoding a soybean NAP-1 homolog, SNAP-1. The SNAP-1 cDNA contains an open reading frame of 358 amino acids residues with a calculated molecular weight of 41 kDa. The deduced amino acid sequence of SNAP-1 shares sequence similarity with yeast NAP-1 (38%) and human hNRP (32%). Notable features of the deduced sequence are two extended acidic regions thought to be involved in histone binding. SNAP-1 expressed in Escherichia coli induces supercoiling in relaxed circular DNA, suggesting that SNAP-1 may have nucleosome assembly activity. The specific activity of SNAP-1 is comparable to that of HeLa NAP-1 in an in vitro assay. Western analysis reveals that SNAP-1 is expressed in the immature and young tissues that were examined, while mature tissues such as old leaves and roots, show very little or no expression. NAP-1 homologs also appear to be present in other plant species.

Amino Acid Sequence↗
PubMed1995

Identification of a novel divergent calmodulin isoform from soybean which has differential ability to activate calmodulin-dependent enzymes.

Calmodulin plays pivotal roles in the transduction of various Ca(2+)-mediated signals and is one of the most highly conserved proteins in eukaryotic cells. In plants, multiple calmodulin isoforms with minor amino acid sequence differences were identified but their functional significances are unknown. To investigate the biological function of calmodulins in the regulation of calmodulin-dependent enzymes, we cloned cDNAs encoding calmodulins in soybean. Among the five cDNAs isolated from soybean, designated as SCaM-1 to -5, SCaM-4 and -5 encoded very divergent calmodulin isoforms which have 32 amino acid substitutions from the highly conserved calmodulin, SCaM-1 encoded by SCaM-1 and SCaM-3. SCaM-4 protein produced in Escherichia coli showed typical characteristics of calmodulin such as Ca(2+)-dependent electrophoretic mobility shift and the ability to activate phosphodiesterase. However, the extent of mobility shift and antigenicity of SCaM-4 were different from those of SCaM-1. Moreover, SCaM-4 did not activate NAD kinase at all in contrast to SCaM-1. Also there were differences in the expression pattern of SCaM-1 and SCaM-4. Expression levels of SCaM-4 were approximately 5-fold lower than those of SCaM-1 in apical and elongating regions of hypocotyls. In addition, SCaM-4 transcripts were barely detectable in root whereas SCaM-1 transcripts were as abundant as in apical and elongating regions of hypocotyls. In conclusion, the different biochemical properties together with differential expression of SCaM-4 suggest that this novel calmodulin may have different functions in plant cells.

Animals↗
PubMed1995

Isolation of two soybean G-box binding factors which interact with a G-box sequence of an auxin-responsive gene.

G-box binding factors (GBFs) constitute a family of plant DNA-binding proteins that bind to the G-box motif, a regulatory cis element present in many plant genes with a palindromic DNA motif of CACGTG. Previously TCCACGTGTC, a G-box motif, from an auxin responsive gene GmAux28 has been identified as a sequence-specific protein-binding site. Here the isolation of two soybean cDNA clones, referred to as SGBF-1 and SGBF-2, encoding proteins which bind to the G-box motif is reported. The primary structure of SGBF-1 and SGBF-2 predicts that these proteins contain a basic leucine zipper (bZIP) DNA-binding domain and an N-terminal proline-rich domain. A dramatic difference in the pattern of protein-DNA complex formation was observed when recombinant SGBF-1 and SGBF-2 proteins were analyzed by electrophoretic mobility shift assays (EMSAs). The SGBF-1 binding pattern obtained with the G-box probe resulted in three major retarded bands while the SGBF-2 formed a single complex. This shows that the characteristically diffuse banding pattern of plant nuclear proteins interacting with the G-box is also observed in a binding assay using only one recombinant GBF. EMSAs were performed with a few selected binding sequences to study the effect of flanking nucleotides to the hexanucleotide G-box core motif. The binding specificity of the SGBF proteins resembles that described for type A cauliflower nuclear G-box binding proteins which bind class I G-box elements [(G/T)(C/A)CACGTG(G/T)(A/C)]. Phylogenetic analysis of 13 GBF-like proteins from various plant species reveals that the SGBF-1 and SGBF-2 proteins belong to different lineages, suggesting that they may have distinct functions in activating transcription.

Amino Acid Sequence↗