Metabolic Compartmentation of Vertebrate Glutamine          Synthetase
{'Code': '08090300', 'Directorate': {'LongName': 'Direct For Biological Sciences'}, 'Division': {'LongName': 'Division Of Integrative Organismal Systems'}}
{'SignBlockName': 'Machi F. Dilworth'}
The overall goal of this project is an elucidation of the                  possible molecular events that led to the mitchondrial                          compartmentation of glutamine synthetase in liver tissue during                 vertebrate evolution.  This localization of the enzyme allowed                  for the development of uricoteley as a major kind of excretory                  nitrogen metabolism.  Most mitochondrial proteins are coded for                 in the nucleus, translated in cytosol, and targeted to                          mitochondria by N-terminal signal sequences.  The larger size of                the pre-enzyme allows it to be distinguished from the mature                    enzyme.  We have shown this to probably be true for elasmobranch                liver mitochondrial glutamine synthetase and we now intend to                   characterize the import of the pre-enzyme by elasmobranch liver                 mitochondria in vivo and in vitro.  We have also found that in                  birds and alligators there is no detectable size difference                     between the nascent and mature glutamine synthetase peptide in                  liver, despite its mitochondrial matrix localization in tissue.                 In order to determine if there is an internal targeting sequence                in the avian enzyme, we will clone and sequence glutamine                       synthetase mRNA cDNA from both liver and brain.  The enzyme                     remains in the cytosol in the latter tissue so a comparison of                  the deduced amino acid sequences for the two should give some                   clue as to the nature and location of the signal sequence used                  for import of the liver enzyme.  We also will obtain the deduced                sequences for elasmobranch and possibly tortoise pre-glutamine                  synthetase for comparative purposes.  This comparison should give               some indication of the possible changes that have occured during                evolution that led from a classical presequence mechanism for                   targeting of the enzyme to liver mitochondria in primitive                      vertebrates to whatever the mechanism used in higher uricotelic                 vertebrates.                                                                                                                                                         This research on the molecular mechanisms of how enzymes are               targeted to specific cell compartments is significant to cell                   biology and biochemistry.  The regulation of enzyme activity is a               key question for understanding metabolism.//
{'FirstName': 'James', 'LastName': 'Campbell', 'EmailAddress': None, 'StartDate': '04/01/1988', 'EndDate': None, 'RoleCode': 'Principal Investigator'}
{'Name': 'William Marsh Rice University', 'CityName': 'Houston', 'ZipCode': '770051827', 'PhoneNumber': '7133484820', 'StreetAddress': '6100 MAIN ST', 'CountryName': 'United States', 'StateName': 'Texas', 'StateCode': 'TX'}
[{'Code': '1145', 'Text': 'INTEGRATIVE PLANT BIOLOGY'}, {'Code': '9120', 'Text': 'CROSS-DIRECTORATE PROGRAMS'}, {'Code': '9145', 'Text': 'SPECIAL PROGRAMS-RESERVE'}]
{'url': 'https://www.nsf.gov/awardsearch/download?DownloadFileName=1987&All=true', 'xml': '8718042.xml'}