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Query: UNIPROT:P06889 (Mol)
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The maize rab17 gene is expressed in different plant parts in response to ABA and osmotic stress (J. Vilardell et al., Plant Mol Biol 14 (1990) 423-432). Here we demonstrate that 5' upstream sequences of the rab17 gene confer the appropriate patterns of expression on the chloramphenicol acetyl transferase (CAT) reporter gene in transgenic tobacco plants, as well as in protoplasts derived from cultured rice cells. Specifically, a CAT construct containing a large 5' upstream fragment of rab17 (-1330/+29) results in high levels of CAT activity in embryos, leaves and roots of transgenic plants subjected to water stress or ABA treatment. Transient expression assays in rice protoplasts transfected with CAT genes fused to rab17 promoter deletions indicate that a 300 bp DNA fragment (-351/-102) is sufficient to confer ABA responsiveness upon the reporter gene. Furthermore, a 100 bp sequence (-219/-102) is capable of conferring ABA responsiveness upon a minimal promoter derived from the 35S CaMV promoter. Gel retardation experiments indicate that maize nuclear proteins bind to this fragment. This region of 100 bp contains a sequence (ACGTGGC) which has been identified as an abscisic acid response element in studies of other ABA-responsive plant genes.
Plant Mol Biol 1991 Nov
PMID:Regulation of the maize rab17 gene promoter in transgenic heterologous systems. 193 88

We have cloned and sequenced the four members of a rice rab (responsive to abscisic acid) gene family that are tandemly arrayed in a locus approximately 30 kbp in length. Each of the genes contains a single, small intron. They are all transcriptionally active and encode proteins of Mr 15,500-16,800 with two highly conserved domains. Northern analysis with gene-specific probes showed slightly different patterns of expression for the four genes in rice plant tissues and in response to osmotic stress. Comparison of the promoter regions revealed a conserved GC-rich sequence (CGG/CCGCGCT) with some homology to the SP1 binding site (Briggs et al., 1986). Another conserved sequence (PuTACGTGGCPu), whose core is found in the promoter regions of ABA-responsive cotton genes, is reminiscent of the cAMP responsive element (Deutsch et al., 1988).
Plant Mol Biol 1990 Jan
PMID:Four tightly linked rab genes are differentially expressed in rice. 215 51

The ABA-induced MA12 cDNA from maize, which encodes a set of highly phosphorylated embryo proteins, was used to isolate the corresponding genomic clone. This gene, called RAB-17 (responsive to ABA), encodes a basic, glycine-rich protein (mol. wt. 17,164) containing a cluster of 8 serine residues, seven of them contiguous. It is a homologue of the rice RAB-21 gene (Mundy J, Chua NH, EMBO J 7; 2279-2286, 1988). Phosphoamino acid analysis of the isolated protein indicates that only the serine residues are phosphorylated and a putative casein-type kinase phosphorylatable sequence was identified in the protein. The pattern of expression and in vivo phosphorylation of the RAB-17 protein was studied during maize embryo germination and in calli of both meristematic or embryonic origin. ABA treatment induced the synthesis of RAB-17 mRNA and protein in calli, however, the RAB-17 proteins were found to be highly phosphorylated only in embryos.
Plant Mol Biol 1990 Mar
PMID:Gene sequence, developmental expression, and protein phosphorylation of RAB-17 in maize. 215 15

A1 adenosine receptors in bovine cerebral cortex have been solubilized and subjected to sedimentation analysis using sucrose density gradient centrifugation. Because the receptors bound both agonists and antagonists with high affinity after solubilization, receptors labeled with an agonist or an antagonist radioligand could be studied before solubilization, after solubilization but before sucrose gradient centrifugation, or after sucrose gradient centrifugation. In each instance the agonist radioligand 125I-N6-p-aminobenzyladenosine (125I-ABA)-labeled receptor migrated as a single symmetrical peak that was located in the same area of the gradient. In contrast, the location of the receptor labeled with the antagonist [3H]xanthine amine congener [( 3H]XAC) varied in the different types of samples. When membranes were incubated with radioligands before solubilization, the peak of antagonist-labeled receptor was symmetrical and was located at a lower density than the peak of agonist-labeled receptor. In addition, receptors incubated with antagonist before solubilization migrated with an apparent lower density than receptors labeled with antagonist either after solubilization or after density gradient centrifugation. Treatments with agents that alter receptor/G protein interactions also resulted in a shift of antagonist-labeled receptors to lower density. These results suggest that the receptors that migrate to the lower density fractions of the gradients are free receptors, whereas those that migrate to the higher density fractions are coupled to a G protein. It is hypothesized that a large proportion of A1 receptors exist in the membrane coupled to a G protein and that this is the species labeled by the agonist radioligand 125I-ABA. It is, furthermore, hypothesized that the antagonist radioligand [3H]XAC preferentially binds to the free uncoupled A1 receptors.(ABSTRACT TRUNCATED AT 250 WORDS)
Mol Pharmacol 1989 Sep
PMID:Density gradient profiles of A1 adenosine receptors labeled by agonist and antagonist radioligands before and after detergent solubilization. 250 30

Several cDNAs related to an ABA-induced cDNA from barley aleurone were isolated from barley and corn seedlings that were undergoing dehydration. Four different barley polypeptides with sizes of 22.6, 16.2, 14.4 and 14.2 kDa and a single corn polypeptide with a size of 17.0 kDa were predicted from the nucleotide sequences of the cDNAs. These dehydration-induced proteins (dehydrins) are very similar to each other and to a previously identified rice protein induced by ABA and salt, and have at least some similarity to a previously identified cotton embryo protein. Each dehydrin is extremely hydrophilic, glycine-rich, cysteine- and tryptophan-free and contains repeated units in a conserved linear order. A lysine-rich repeating unit occurs twice in each protein, once at the carboxy terminus and once partway through the polypeptide, adjacent to a succession of serines. This repeating unit and the adjacent flanking run of serines are conserved with minimal variation among all dehydrins. Another repeating unit is flanked by the two copies of the lysine-rich unit, and varies in number from one to five copies. This latter repeating unit is less conserved than the former, varying even within a singly dehydrin. The messenger RNAs corresponding to each cDNA are abundant in dehydrating, but not in well-watered seedlings. The amino acid sequence of tryptic peptides from purified dehydration-induced proteins of corn established that the corn cDNAs correspond to a protein that is produced in abundance during the response of corn seedlings to dehydration.
Plant Mol Biol 1989 Jul
PMID:A cDNA-based comparison of dehydration-induced proteins (dehydrins) in barley and corn. 256 63

Structural features influencing opioid activity of enkephalin analogs were investigated through the synthesis and evaluation of opioid receptor binding affinities of a series of cyclic dithioether-containing analogs and structurally related linear analogs of the cyclic, disulfide-containing peptides, [D-Pen2, D-Pen5]enkephalin and [D-Pen2, L-Pen5]enkephalin, where Pen (penicillamine) is beta, beta-dimethylcysteine. The major effect of increasing the ring size of the cyclic moiety from disulfide to dithioether analogs was a large decrease in delta opioid receptor binding affinity which suggests that relatively compact conformations of the peptide ligand are necessary for optimal binding to this receptor. The effect of bulky, hydrophobic residues at position 2 in the peptide chain was evaluated by preparing the linear analogs, [D-t-Leu2, D-t-Leu5]enkephalin (t-Leu, 2-amino-3,3-dimethylbutanoic acid) and [D-Abu2, D-t-Leu5]enkephalin (Abu, 2-aminobutanoic acid). The former analog was found to be 36- and 450-fold less potent at delta and mu receptor sites, respectively, than was the latter, suggesting that bulky side chain substituents in position 2 of enkephalin analogs lead to a deleterious steric interaction at delta and particularly at mu receptors.
Mol Pharmacol 1987 Jun
PMID:Structural requirements for delta opioid receptor binding. 303 96

Our previous study demonstrated (1) that the presence of charged groups (amino and carboxyl groups) at the alpha-carbon of tyrosine is essential for activation of azobenzenearsonate-L-tryosine (ABA-L-Tyr specific T cells, and (2) that T cells recognizes ABA-L-Tyr in association with macromolecules on syngeneic spleen cells used as antigen presenting cells (APC). The present study was undertaken to confirm that the macromolecules on APC are Ia molecules, by using L cells transfected with A beta k and A alpha k genes as APC. I-Ak restricted ABA-L-Tyr specific cloned T cells, and T hybridoma cells were activated by ABA-L-Tyr in the presence of the L cell transfectants, of which expression of I-Ak molecules had been proven by specific binding of anti-I-Ak monoclonal antibody (MAb) 10.2.16 on the cell surface. The pattern of responses of I-Ak restricted ABA-L-Tyr specific T cells to various ABA-Tyr derivatives presented by the I-Ak expressing L cell transfectants was similar to the pattern obtained by using H-2k spleen cells as APC. Thus, ABA-L-Tyr and ABA-Tyr derivatives, which have both amino and carboxyl groups at the alpha-carbon of Tyr, presented by the L cell transfectants triggered good response of I-Ak restricted ABA-L-Tyr specific T cells. By contrast, ABA-Tyr derivatives, which lack the amino or carboxyl group, or both groups, at the alpha-carbon of Tyr, presented by the L cell transfectants could not activate the ABA-L-Tyr specific T cells at all. Furthermore, anti-I-Ak MAb, but not anti-I-Ek MAb, inhibited completely the response of I-Ak restricted ABA-L-Tyr specific T cells to ABA-L-Tyr presented by the L cell transfectants. These results indicate strongly that the macromolecules on APC which associate with ABA-L-Tyr are A beta k A alpha k gene products, i.e., I-Ak molecules.
Mol Immunol 1988 Jun
PMID:Mode of antigen presentation required for triggering of T cell response: analysis by use of azobenzenearsonate-tyrosine derivatives as antigens and L cells transfected with I-Ak genes as antigen presenting cells. 313 94

Two anti-phenyloxazolone (phOx3) and one anti-GAT MAbs from C57BL mice are shown to be coded by VH gene 186.2. This gene has been found earlier to code for several anti-NP (NNP) antibodies (Bothwell et al., 1981) and anti-GT antibodies (Rocca-Serra et al., 1983; Carmack and Pincus, 1986). The L chain partner of the VH 186.2 gene is different in anti-NP and anti-GAT antibodies (Bothwell et al., 1981; Rocca-Serra et al., 1983; Carmack and Pincus, 1986); in anti-phOx antibodies two new unrelated kappa chain V regions were found. Both of the new VK genes involved code frequently for anti-phOx antibodies in BALB/c mice but then with different VH genes. We tested five 186.2-coded antibodies for cross-reactions. Four antibodies were specific, one bound only to NNP, one only to phOx and two only to GT (GAT). The fifth antibody (anti-phOx) bound also to NNP, GAT and ABA-HOP though probably with a low affinity. This is the first demonstration that one V gene can code for three different antibody specificities. It emphasizes the role of the combinatorial element in antibody diversity.
Mol Immunol 1988 Sep
PMID:Combinatorial association of V genes: one VH gene codes for three non-cross-reactive monoclonal antibodies each specific for a different antigen (phoxazolone, NP or gat). 321 Nov 60

Two mouse X sheep interspecific cell hybrids were obtained by fusing mouse myeloma cell line Sp2/O. Ag14 with sheep lymphocytes obtained from a lymph node antigenically stimulated with azo-benzene arsonate-ovalbumin (ABA-ova). The interspecific cell lines were characterized using immunochemical, karyotypic and molecular DNA techniques. Both cell lines secreted sheep IgG1 antibody specific for the ABA haptenic determinant. Karyotypic analysis revealed that cell lines 4.11 and 11.9 had modal chromosome numbers of 91 and 106, respectively. Although C-banded spreads confirmed that fusion between sheep and mouse cells had occurred, it was not possible to differentiate sheep from mouse chromosomes. However, DNA hybridization techniques showed that each line contained sheep repetitive sequence DNA. It was calculated that cell line 11.9 contained 17640 copies while cell line 4.11 contained 734 copies of the previously characterized sheep satellite DNA.
Mol Immunol 1986 Jul
PMID:Characterization of two mouse myeloma X sheep lymphocyte cell lines secreting sheep antibody. 354 Jun 17

The infrared stretching bands of carboxymyoglobin (MbCO) and the rebinding of CO to Mb after photodissociation have been studied in the temperature range 10-300 K in a variety of solvents. Four stretching bands imply that MbCO can exist in four substates, A0-A3. The temperature dependences of the intensities of the four bands yield the relative binding enthalpies and and entropies. The integrated absorbances and pH dependences of the bands permit identification of the substates with the conformations observed in the X-ray data (Kuriyan et al., J. Mol. Biol. 192 (1986) 133). At low pH, A0 is hydrogen-bonded to His E7. The substates A0-A3 interconvert above about 180 K in a 75% glycerol/water solvent and above 270 K in buffered water. No major interconversion is seen at any temperature if MbCO is embedded in a solid polyvinyl alcohol matrix. The dependence of the transition on solvent characteristics is explained as a slaved glass transition. After photodissociation at low temperature the CO is in the heme pocket B. The resulting CO stretching bands which are identified as B substates are blue-shifted from those of the A substates. At 40 K, rebinding after flash photolysis has been studied in the Soret, the near-infrared, and the integrated A and B substates. All data lie on the same rebinding curve and demonstrate that rebinding is nonexponential in time from at least 100 ns to 100 ks. No evidence for discrete exponentials is found. Flash photolysis with monitoring in the infrared region shows four different pathways within the pocket B to the bound substates Ai. Rebinding in each of the four pathways B----A is nonexponential in time to at least 10 ks and the four pathways have different kinetics below 180 K. From the time and temperature dependence of the rebinding, activation enthalpy distributions g(HBA) and preexponentials ABA are extracted. No pumping from one A substate to another, or one B substate to another, is observed below the transition temperature of about 180 K. If MbCO is exposed to intense white light for 10-10(3) s before being fully photolyzed by a laser flash, the amplitude of the long-lived states increases. The effect is explained in terms of a hierarchy of substates and substate symmetry breaking. The characteristics of the CO stretching bands and of the rebinding processes in the heme pocket depend strongly on the external parameters of solvent, pH and pressure. This sensitivity suggests possible control mechanisms for protein reactions.
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PMID:Rebinding and relaxation in the myoglobin pocket. 360 34


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