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1.
The distribution of grooming and touching behaviours was recorded in a group of captive ring-tailed lemurs. Grooming was found
to be performed chiefly by older, higher ranking animals; touching (i.e., “reach out and touch” behaviour) was directed primarily
by younger, low ranking animals to older, high ranking individuals. It is suggested that such touching is a submissive gesture
in this species. 相似文献
2.
Dihydropyridine and phenylalkylamine receptors associated with cardiac and skeletal muscle calcium channels are structurally different 总被引:1,自引:0,他引:1
We have purified putative L-type Ca2+ channels from chick heart by virtue of their associated high affinity receptors for the Ca2+ channel effectors, dihydropyridines (DHPs), and phenylalkylamines (PAAs). A peptide of 185,000-190,000 daltons was found to comigrate with the peak of DHP binding activity during purification through two successive cycles of lectin affinity chromatography and sucrose density gradient centrifugation. A previously described peptide of 140,000 daltons, whose Mr was increased to approximately 180,000 under nonreducing conditions, also copurified with the 185-kDa peptide and dihydropyridine binding activity. When cardiac membranes were photolabeled with either the dihydropyridine [3H]azidopine or the PAA [3H]azidopamil prior to purification, a single, specifically labeled component of 185,000-190,000 daltons was present in the purified fractions. The properties of this 185-kDa cardiac DHP/PAA receptor were compared to the smaller 165-kDa DHP/PAA receptor previously purified from skeletal muscle. Antibodies raised against the 165-kDa skeletal muscle DHP/PAA receptor reacted with both rabbit and chick skeletal muscle receptors, but only poorly recognized, if at all, the cardiac 185-190 kDa component. The 185-kDa peptide present in the purified fractions obtained from cardiac muscle did not undergo substantial phosphorylation by cAMP-dependent protein kinase, while the purified 165-kDa peptide from rabbit and chick skeletal muscle was a good substrate for this kinase. The results show that the DHP and PAA receptors in cardiac muscle are contained in a 185-190-kDa peptide that is significantly larger than, and structurally and immunologically different from, it skeletal muscle counterpart. 相似文献
3.
We have broadly defined the DNA regions regulating esterase6 activity in
several life stages and tissue types of D. melanogaster using P-
element-mediated transformation of constructs that contain the esterase6
coding region and deletions or substitutions in 5' or 3' flanking DNA.
Hemolymph is a conserved ancestral site of EST6 activity in Drosophila and
the primary sequences regulating its activity lie between -171 and -25 bp
relative to the translation initiation site: deletion of these sequences
decrease activity approximately 20-fold. Hemolymph activity is also
modulated by four other DNA regions, three of which lie 5' and one of which
lies 3' of the coding region. Of these, two have positive and two have
negative effects, each of approximately twofold. Esterase6 activity is
present also in two male reproductive tract tissues; the ejaculatory bulb,
which is another ancestral activity site, and the ejaculatory duct, which
is a recently acquired site within the melanogaster species subgroup.
Activities in these tissues are at least in part independently regulated:
activity in the ejaculatory bulb is conferred by sequences between -273 and
-172 bp (threefold decrease when deleted), while activity in the
ejaculatory duct is conferred by more distal sequences between -844 and
-614 bp (fourfold decrease when deleted). The reproductive tract activity
is further modulated by two additional DNA regions, one in 5' DNA (-613 to
-284 bp; threefold decrease when deleted) and the other in 3' DNA (+1860 to
+2731 bp; threefold decrease when deleted) that probably overlaps the
adjacent esteraseP gene. Collating these data with previous studies
suggests that expression of EST6 in the ancestral sites is mainly regulated
by conserved proximal sequences while more variable distal sequences
regulate expression in the acquired ejaculatory duct site.
相似文献
4.
Differential phosphorylation of band 3 and glycophorin in intact and extracted erythrocyte membranes
This report presents an analysis of the phosphorylation of human and rabbit erythrocyte membrane proteins which migrate in NaDodSO4-polyacrylamide gels in the area of the Coomassie Blue-stained proteins generally known as band 3. The phosphorylation of these proteins is of interest as band 3 has been implicated in transport processes. This study shows that there are at least three distinct phosphoproteins associated with the band 3 region of human erythrocyte membranes. These are band 2.9, the major band 3, and PAS-1. The phosphorylation of these proteins is differentially catalyzed by solubilized membrane and cytoplasmic cyclic AMP-dependent and -independent erythrocyte protein kinases. Band 2.9 is present and phosphorylated in unfractionated human and rabbit erythrocyte ghosts but not in NaI- or dimethylmaleic anhydride (DMMA)-extracted membranes. These latter membrane preparations are enriched in band 3 and in sialoglycoproteins. The NaI-extracted ghosts contain residual protein kinase activity which can catalyze the autophosphorylation of band 3 whereas the DMMA-extracted ghosts are usually devoid of any kinase activity. However, both NaI- and DMMA-extracted ghosts, as well as Triton X-100 extracts of the DMMA-extracted ghosts, can be phosphorylated by various erythrocyte protein kinases. The kinases which preferentially phosphorylate the major band 3 protein are inactive towards PAS-1 while the kinases active towards PAS-1 are less active towards band 3. The band 3 protein in the DMMA-extracted ghosts can be cross-linked with the Cu2+ -σ-phenanthroline complex. The cross-linking of band 3 does not affect its capacity to serve as a phosphoryl acceptor nor does phosphorylation affect the capacity of band 3 to form cross-links. In addition to band 2.9, the major band 3 and PAS-1, another minor protein component appears to be present in the band 3 region in human erythrocyte membranes. This protein is specifically phosphorylated by the cyclic AMP-dependent protein kinases isolated from the cytoplasm of rabbit erythrocytes. The rabbit erythrocyte membranes lack PAS-1 and the cyclic AMP-dependent protein kinase substrate. 相似文献
5.
The alpha 1 subunit of the dihydropyridine-sensitive calcium channel is a protein which is critical for excitation-contraction coupling and L-type calcium current in skeletal muscle. Using antibodies generated against peptides from three regions of the deduced amino acid sequence of the alpha 1 subunit, we have identified two distinct proteins in rabbit skeletal muscle. Both proteins appeared to be recognized by antibodies against the amino (N) terminus of the alpha 1 subunit sequence. One protein was also recognized by antibodies against an internal (I) region of the predicted sequence but not by antibodies against the carboxyl (C) terminus. In contrast, the other protein was recognized by antibodies against the carboxyl terminus but not by the antibodies against the internal region. We have designated these proteins pNI and pNC based on their patterns of antibody recognition. No protein was detected which was recognized by all three antibodies. pNI is the protein commonly identified as the alpha 1 subunit of the dihydropyridine-sensitive calcium channel. Of note is that pNI, which apparently lacks sequences from the predicted carboxyl tail, is the protein present in preparations which we have previously demonstrated contain dihydropyridine-sensitive calcium channel activity. pNC is herein identified as a skeletal muscle protein that is immunologically related to the alpha 1 subunit of the dihydropyridine-sensitive calcium channel. Its function is unknown. In addition to their distinct patterns of antibody recognition, pNI and pNC were also distinguishable by several other properties. pNC migrated as a protein of approximately 160 kDa in 5% sodium dodecyl sulfate-polyacrylamide gels versus approximately 165 kDa for pNI. pNI was enriched in transverse tubule membranes, whereas pNC was found to be enriched in triad and junctional sarcoplasmic reticulum membrane fractions and was not found in transverse tubule membranes. Under conditions in which pNI bound to wheat germ agglutinin-Sepharose, pNC did not bind. The results demonstrate that there are two proteins in skeletal muscle which are immunologically related to the alpha 1 subunit of the dihydropyridine-sensitive calcium channel but which are distinguishable by several biochemical and immunological characteristics. 相似文献
6.
The human m1 (hm1) and m2 (hm2) muscarinic cholinergic receptors (mAChR) expressed in Sf9 insect cells using recombinant baculovirus were tested for their ability to undergo agonist-dependent phosphorylation and desensitization. The muscarinic agonist carbachol induced phosphorylation of the hm2 mAChR in the Sf9 cells incubated with 32P(i) to an extent of 4-5 mol of phosphate/mol of receptor. In contrast, no phosphorylation of the hm1 mAChR was observed. The hm2 mAChR stimulated [35S]GTP gamma S binding to, and GTPase activity of, the insect cell G-proteins. These receptor-mediated activities were reduced by 50% in membranes prepared from agonist-treated cells compared to control, suggesting that the agonist-induced phosphorylation of the hm2 mAChR resulted in desensitization of the receptors. No role for protein kinase C or cyclic nucleotide-dependent kinases in receptor phosphorylation and desensitization was suggested from studies using agents known to modulate the activity of these enzymes. However, pertussis toxin was found to completely eliminate the interaction of the hm2 receptors with the insect cell G-proteins, but did not perturb the ability of carbachol to induce agonist-dependent phosphorylation of the receptors. These results suggested that G-proteins and/or G-protein-activated signalling were not necessary for the agonist-induced phosphorylation of the receptors. Overall, the data indicated that the human m2 (but not the human m1) mAChR expressed in Sf9 insect cells undergo phosphorylation and desensitization in an agonist-dependent, G-protein-independent fashion by an endogenous insect cell kinase. The results demonstrated that a human G-protein-linked receptor is regulated in insect cells in a manner that is similar to that involving members of the G-protein receptor-kinase family. 相似文献
7.
8.
A covalently bound photoisomerizable agonist. Comparison with reversibly bound agonists at electrophorus electroplaques 总被引:2,自引:2,他引:0 下载免费PDF全文
HA Lester ME Krouse MM Nass NH Wassermann BF Erlanger 《The Journal of general physiology》1980,75(2):207-232
After disulphide bonds are reduced with dithiothreitol, trans-3- (α-bromomethyl)-3’-[α- (trimethylammonium)methyl]azobenzene (trans-QBr) alkylates a sulfhydryl group on receptors. The membrane conductance induced by this “tethered agonist” shares many properties with that induced by reversible agonists. Equilibrium conductance increases as the membrane potential is made more negative; the voltage sensitivity resembles that seen with 50 [mu]M carbachol. Voltage- jump relaxations follow an exponential time-course; the rate constants are about twice as large as those seen with 50 μM carbachol and have the same voltage and temperature sensitivity. With reversible agonists, the rate of channel opening increases with the frequency of agonist-receptor collisions: with tethered trans-Qbr, this rate depends only on intramolecular events. In comparison to the conductance induced by reversible agonists, the QBr-induced conductance is at least 10-fold less sensitive to competitive blockade by tubocurarine and roughly as sensitive to “open-channel blockade” bu QX-222. Light-flash experiments with tethered QBr resemble those with the reversible photoisomerizable agonist, 3,3’,bis-[α-(trimethylammonium)methyl]azobenzene (Bis-Q): the conductance is increased by cis {arrow} trans photoisomerizations and decreased by trans {arrow} cis photoisomerizations. As with Bis-Q, ligh-flash relaxations have the same rate constant as voltage-jump relaxations. Receptors with tethered trans isomer. By comparing the agonist-induced conductance with the cis/tans ratio, we conclude that each channel’s activation is determined by the configuration of a single tethered QBr molecule. The QBr-induced conductance shows slow decreases (time constant, several hundred milliseconds), which can be partially reversed by flashes. The similarities suggest that the same rate-limiting step governs the opening and closing of channels for both reversible and tethered agonists. Therefore, this step is probably not the initial encounter between agonist and receptor molecules. 相似文献
9.
This report presents studies on the effect of diamide on protein phosphorylation in erythrocyte membranes. Diamide, a thiol-oxidizing reagent, nonspecifically inhibits cyclic Amp-dependent and -independent autophosphorylation of red cell memvranes, but not the activity of the solubilized membrane cycle AMP-independent protein kinases. Analysis of diamide-treated membranes by gel electrophoresis indicates that diamide is capable of inducing cross-linking of membrane proteins. The action of diamide, both in the inhibition of membrane autophosphorylation and in the cross-linking of membrane proteins, is very similar to that of Cu2+. o-phenanthroline complex. Our data indicate that diamide inhibits erythrocyte membrane autophosphorylation by perturbing the protein substrates. 相似文献