![[Feedback]](/icons/banner/feedbackACT.gif){kind=icon}
![[For Subscribers]](/icons/banner/subscriberACT.gif){kind=icon}
![[Archive]](/icons/banner/archiveACT.gif){kind=icon}
![[Search]](/icons/banner/searchACT.gif){kind=icon}
![[Contents]](/icons/banner/tocACT.gif){kind=icon}
|
|
|
|
|
||
T Reisine, H Kong, K Raynor, H Yano, J Takeda, K Yasuda and GI Bell
Department of Pharmacology, University of Pennsylvania School of Medicine, Philadelphia 19104.
The diverse biological actions of somatostatin (SRIF) are mediated by a family of receptors, of which five have been cloned and characterized. One of the SRIF receptor subtypes, SSTR2, has been shown to exist in two forms. SSTR2A and SSTR2B are 369 and 346 amino acids in size, respectively, and differ in length and amino acid sequence in their intracellularly located carboxyl termini. SSTR2A and SSTR2B are generated by alternative splicing of SSTR2 mRNA. We previously characterized mouse SSTR2A and showed that it could be distinguished from other cloned SRIF receptor subtypes by its high affinity for MK- 678 and its lack of coupling to adenylyl cyclase. To determine whether the properties of mouse SSTR2A and SSTR2B differ, we have expressed both in COS-7 cells and characterized their ligand-binding properties and ability to couple to adenylyl cyclase. The two receptors exhibited similar affinities for a number of SSTR2-selective agonists such as MK- 678. Pretreatment with SRIF of COS-7 cells expressing each receptor reduced high affinity agonist binding to both SSTR2A and SSTR2B, indicating that both receptors can be regulated. Furthermore, agonist binding to both receptors was reduced by GTP analogs and Na+, indicating that they both associate with G proteins. As shown previously, SSTR2A could not mediate SRIF inhibition of forskolin- stimulated cAMP formation. In contrast, SSTR2B was coupled to adenylyl cyclase and was able to mediate SRIF inhibition of forskolin-stimulated cAMP formation. Thus, SSTR2A and SSTR2B differ in their ability to couple to adenylyl cyclase. Because SSTR2A and SSTR2B differ only in the length and amino acid sequence of their carboxyl termini, these findings imply that the carboxyl-terminal 15 residues of SSTR2B may be involved in coupling this receptor to adenylyl cyclase.
This article has been cited by other articles:
|
|
 |
|
  D. Yang, L. Han, and V. Kundra Exogenous Gene Expression in Tumors: Noninvasive Quantification with Functional and Anatomic Imaging in a Mouse Model Radiology, June 1, 2005; 235(3): 950 - 958. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 V. Chaipatikul, H. H. Loh, and P. Y. Law Ligand-Selective Activation of {micro}-Opioid Receptor: Demonstrated with Deletion and Single Amino Acid Mutations of Third Intracellular Loop Domain J. Pharmacol. Exp. Ther., June 1, 2003; 305(3): 909 - 918. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 V. Kundra, F. Mannting, A. G. Jones, and A. I. Kassis Noninvasive Monitoring of Somatostatin Receptor Type 2 Chimeric Gene Transfer J. Nucl. Med., March 1, 2002; 43(3): 406 - 412. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 J. C. Reubi, A. Kappeler, B. Waser, J. Laissue, R. W. Hipkin, and A. Schonbrunn Immunohistochemical Localization of Somatostatin Receptors sst2A in Human Tumors Am. J. Pathol., July 1, 1998; 153(1): 233 - 245. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 Y.-Z. Gu and A. Schonbrunn Coupling Specificity between Somatostatin Receptor sst2A and G Proteins: Isolation of the Receptor-G Protein Complex with a Receptor Antibody Mol. Endocrinol., May 1, 1997; 11(5): 527 - 537. [Abstract] [Full Text]
|
|
|
|
 |
|
 P. Dournaud, Y. Z. Gu, A. Schonbrunn, J. Mazella, G. S. Tannenbaum, and A. Beaudet Localization of the Somatostatin Receptor SST2A in Rat Brain Using a Specific Anti-Peptide Antibody J. Neurosci., July 15, 1996; 16(14): 4468 - 4478. [Abstract] [Full Text] [PDF]
|
|
 |
 |
 |
|
 |
 |
 |
