ISSN:0730-2312    

DOI:10.1002/jcb.240260302

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1984

数据来源: WILEY

摘要:

AbstractTo understand the regulation of the production of peptide hormones, it is vital to elucidate their biosynthetic pathways. We chose to study a major regulatory peptide, vasoactive intestinal peptide (VIP), a peptide possessing both neurotransmitter and neurohormone actions. To identify the specific peptide mRNA we are using, as hybridization probes, radiolabeled synthetic oligodcoxynucleotides with sequence complementary to the predicted peptide mRNA sequence. Employing this approach, we identified and partially purified a ∼ 1600‐base long mRNA containing VIP related sequences which can be translatedin vitrointo VIP‐immunoreactive polypeptides. Such mRNA was detected in normal VIP producing tissue (rat brain), as well as in a tumor producing VIP (human buccal tumor). This mRNA differs in size from a known VIP‐mRNA identified in human neuro‐blastoma cells, suggesting the possibility of different VIP‐mRNAs in different

ISSN:0730-2312    

DOI:10.1002/jcb.240260303

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1984

数据来源: WILEY

摘要:

AbstractThe major glycoproteins synthesized by human breast epithelial cells have been characterized [6,8]. The most consistently observed and prominent component in supernatants of organ cultures of breast surgical specimens and of MCF‐7 cells was gp 68 which has been immunologically identified as α‐1‐antichymotrypsin (Achy). In the present study we demonstrate that this glycoprotein can form an irreversible complex with chymotrypsin, which indicates that it is a functional inhibitor. The14C‐glucosamine‐labeled gp 68 forms a stable, 88,000‐dalton. enzyme‐inhibitor complex with chymotrypsin. The molecule is secreted continuously for 9 days into a chemically defined, serum‐free medium. In addition to the de novo synthesized inhibitor, another component is adsorbed from fetal bovine scrum and subsequently released into serum‐free medium. This component also forms an irreversible, 88,000‐dalton complex with enzyme. The observations establish that two types of inhibitors are associated with human breast epithelial cells, one actively synthesized and the other derived from serum. Both of these molecules may have significant roles in stabilizing cell surface components and in protecting extracellular matrices from

ISSN:0730-2312    

DOI:10.1002/jcb.240260304

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1984

数据来源: WILEY

摘要:

AbstractBoth the insulin receptor and the gene product of the Rous sarcoma virus, pp60src, are protein kinases which phosphorylate themselves and other proteins on tyrosinc residues. Addition of the solubilized insulin receptor to purified pp60srcincreased the phosphorylation of the β‐subunit of the insulin receptor. Phosphorylation of the insulin receptor by pp60srcoccurred both in the absence and presence of insulin but did not alter the insulin dose response for autophosphorylation of the receptor. Increasing concentrations of pp60srcincreased the phosphorylation of the receptor and at high concentrations equaled the maximal effect produced by insulin. Our observations suggest a possible mechanism by which the metabolically regulated insulin receptor tyrosine kinase could be altered by other tyrosine kinases such as that associated with pp60src. Further studies will be required to determine if the insulin receptor is phosphorylated by pp60srcin Rous sarcoma virus‐infected c

ISSN:0730-2312    

DOI:10.1002/jcb.240260305

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1984

数据来源: WILEY

摘要:

AbstractTo determine the role of thrombin high‐affinity receptor occupancy and enzymic activity in thrombin initiation of cell proliferation, we have utilized thrombin derivatives which separate these functions. We previously showed that enzymically active γ‐thrombin stimulates ion fluxes without binding to high‐affinity sites, whereas proteolytically inhibited DIP‐α‐thrombin which binds to high‐affinity receptors does not. Since neither derivative initiates DNA synthesis by itself, this suggested that two separate sequences of events might be necessary for a complete initiation signal. We now report that the combination of DIP‐α‐thrombin and γ‐thrombin initiate DNA synthesis and cell proliferation to levels approaching the maximal initiation by native α‐thrombin. This combinatory effect is dose‐dependent for both γ‐thrombin and DIP‐α‐thrombin in the same concentration range as α‐thrombin alone. Thus, these same concentrations of α‐thrombin alone may be required to initiate each sequence of events. The combinatory stimulation could be achieved even if the derivatives were added individually up to 8 hr apart. Moreover, preincubation with either derivative shortened the lag period for initiation of DNA synthesis by native α‐thrombin. These results indicate that both receptor occupancy and enzymic activity are necessary for thrombin initiation of cell proliferation and that each action initiates a sequence of early events which moves the cell forw

ISSN:0730-2312    

DOI:10.1002/jcb.240260306

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1984

数据来源: WILEY

摘要:

AbstractThe “enzyme‐probe” method [Solti M, Friedrich P: Eur J Biochem 95:551, 1979] has been applied to characterize the cyclic AMP pool in wild‐type Canton‐S and memory‐mutant dunceM11strains of Drosophila melanogaster. The kinetics of cyclic AMP breakdown in whole fly homogenates by endogenous cyclic nucleo‐tide phosphodiesterase(s) indicate that the cyclic AMP pool is divided into free and bound fractions. The bound fraction in Canton‐S and dunceM11is 0.5 and 1.5 pmole/mg fly, respectively. Considering the total cyclic AMP content of the two strains, 1.6 and 10 pmole/mg fly, respectively, we conclude that the bulk of excess cyclic AMP in the mutant is

ISSN:0730-2312    

DOI:10.1002/jcb.240260307

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1984

数据来源: WILEY

ISSN:0730-2312    

DOI:10.1002/jcb.240260301

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1984

数据来源: WILEY