Nucleoside diphosphate kinase associated with rat pancreatic membranes regulates CCK receptor affinity.
Nucleoside diphosphate kinase associated with rat pancreatic membranes regulates CCK receptor affinity.
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与大鼠胰膜相关的核苷二磷酸激酶调节 CCK 受体亲和力。
DOI：
10.1152/ajpgi.1994.267.5.g866
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发表时间：
1994
期刊：
影响因子：
--
通讯作者：
Williams,JA
中科院分区：
文献类型：
--
作者：
BlevinsJr,GT;vandeWesterlo,EM;Williams,JA
我们先前已经证明，在透化大鼠胰腺腺泡中，完整细胞中所见的胰腺胆囊收缩素（CCK）受体的两种亲和力状态的存在取决于ATP的存在。在本研究中，我们证明ATP的这种作用是由核苷二磷酸激酶（NDPK）介导的。北方杂交显示胰腺NDPK mRNA表达。此外，胰腺膜具有NDPK活性，其将高能磷酸基团转移到[8- 3 H]GDP。该酶还利用UTP和ITP作为GTP形成的γ-磷酸源，而鸟苷5 '-O-（3-硫代三磷酸）（GTP γ S）在腺苷5'-O-（3-硫代三磷酸）（ATP γ S）存在下形成。然而，腺苷酰（β，γ-亚甲基）-二磷酸（AMP-PCP）没有作为NDPK的底物。在不存在核苷酸的情况下，125 I-Bolton-Hunter标记的CCK八肽（[125 I]BH-CCK-8）结合数据的分析与解离常数（Kd）等于80 pM且最大结合等于50.8 fmol/mg的单一亲和状态一致。ATP、UTP、ITP、ATP γ S和GTP γ S均诱导两种CCK结合亲和力状态，在1 mM ATP存在下，高亲和力位点的Kd = 74 pM，低亲和力位点的Kd = 4.3 nM：AMP-PCP未诱导两种亲和力状态。10 μ M的GDP对CCK结合没有影响，但增强了ATP的作用。GTP γ S，除了诱导高和低亲和力状态，也引起了显着的浓度依赖性减少可测量的CCK受体的总数。（250字处删节）
We have previously demonstrated in permeabilized rat pancreatic acini that the existence of two affinity states of the pancreatic cholecystokinin (CCK) receptor seen in intact cells depends on the presence of ATP. In the present study, we demonstrate that this effect of ATP is mediated by the enzyme nucleoside diphosphate kinase (NDPK). Northern blot hybridization analysis demonstrated NDPK mRNA in pancreas. Furthermore, pancreatic membranes possessed NDPK activity, which transferred high-energy phosphate groups to [8-3H]GDP. This enzyme also utilized UTP and ITP as a source of gamma-phosphate for GTP formation while guanosine 5'-O-(3-thiotriphosphate) (GTP gamma S) was formed in the presence of adenosine 5'-O-(3-thiotriphosphate) (ATP gamma S). However, adenylyl (beta, gamma-methylene)-diphosphate (AMP-PCP) did not serve as a substrate for NDPK. Analysis of 125I-Bolton-Hunter-labeled CCK octapeptide ([125I]BH-CCK-8) binding data in the absence of nucleotides was consistent with a single affinity state with dissociation constant (Kd) equal to 80 pM and maximal binding equal to 50.8 fmol/mg. ATP, UTP, ITP, ATP gamma S, and GTP gamma S all induced two CCK binding affinity states, which in the presence of 1 mM ATP were Kd = 74 pM for high-affinity sites and Kd = 4.3 nM for low-affinity sites: AMP-PCP did not induce two affinity states. GDP at 10 microM had no effect on CCK binding but potentiated the effect of ATP. GTP gamma S, in addition to inducing high- and low-affinity states, also elicited a significant concentration-dependent reduction in the total number of measurable CCK receptors.(ABSTRACT TRUNCATED AT 250 WORDS)