Detail of "59481-23-1"

Reference

Biological activities of tyrosine-containing somatostatin analogs on inhibition of secretion of thyrotropin and growth hormone

Biological activities of tyrosine-containing somatostatin analogs on inhibition of secretion of thyrotropin and growth hormone. Ohashi, Shinichi; Sawano, Shinji; Kokubu, Tomokuni; Gondo, Masaaki; Sakakibara, Kyoichi (Res. Inst. Polym. Text., Yokohama, Japan). Endocrinol. Jpn., 23(5), 435-8 (English) 1976. CODEN: ECJPAE. DOCUMENT TYPE: Journal CA Section: 2 (Hormone Pharmacology) Tyr-somatostatin [59481-23-1], [Tyr6]-somatostatin [59481-24-2], [Tyr7]-somatostatin [59481-25-3], and [Tyr11]-somatostatin [59481-27-5] possessed almost the same potency in inhibiting TSH [9002-71-5] release stimulated by TSH-releasing hormone [9015-91-2] as that of cyclic somatostatin [38916-34-6] in rats. [Tyr8]-somatostatin [61617-51-4] had a potency <0.5% of cyclic somatostatin. The tyrosine-contg. somatostatin also inhibited Nembutal-induced growth hormone [9002-72-6] secretion. Apparently, the Ph group of phenylalanine in position 6,7, and 11 of somatostatin is a prerequisite for full activity, whereas the indole of tryptophan in position 8 is important for activity.

The somatostatin receptor on isolated pancreatic acinar cell plasma membranes

The somatostatin receptor on isolated pancreatic acinar cell plasma membranes. Identification of subunit structure and direct regulation by cholecystokinin. Sakamoto, Choitsu; Goldfine, Ira D.; Williams, John A. (Cell Biol. Lab., Mt. Zion Hosp., San Francisco, CA 94120, USA). J. Biol. Chem., 259(15), 9623-7 (English) 1984. CODEN: JBCHA3. ISSN: 0021-9258. DOCUMENT TYPE: Journal CA Section: 2 (Mammalian Hormones) Cyclic somatostatin [38916-34-6] binding to its receptors on rat pancreatic acinar membranes was characterized with 125I-labeled tyrosine-somatostatin [59481-23-1]. Binding at 24° was rapid, reaching a max. after 60 min and was reversible on the addn. of 1 mMm unlabeled ligand. Scatchard anal. revealed a single class of binding sites, with an apparent dissocn. const. of 0.32 nM and a binding capacity of 600 fmol/mg protein. Specificity for somatostatin was demonstrated with the inhibition of labeled hormone binding by somatostatin analogs in proportion to their biol. activities. When 125I-labeled tyrosine-somatostatin was crosslinked too its receptors with the photoreactive cross-linker n-hydroxysuccinimidyl-4-azidobenzoate, the hormone was assocd. with 90,000-mol.-wt. protein. Similar mobilities of the radioactive band were obsd. in the presence and absence of dithiothreitol. In contrast to other unrelated peptides, cholecystokinin (CCK) [9011-97-6] and its analogs directly reduced 125-labeled tyrosine-somatostatin binding to isolated membranes. The effect of CCK was half-maximal at 3 nM and maximal at 100 nM. In the presence of 3 nM cholecystokinin octapeptide [25126-32-3] (CCK8), the binding capacity for somatostatin was decreased to 237 fmol/mg protein without a significant change in affinity. Dibutyryl cGMP [32266-35-6], a CCK receptor antagonist, blocked this action of CCK8 indicating that the CCK receptor mediated the decrease in 125I-labeled tyrosine-somatostatin binding. In contrast cerebral cortex membranes, which also possess a somatostatin receptor, were not regulated by CCK. The binding of somatostatin to its receptor on pancreatic plasma membranes is apparently regulated by CCK analogs acting via the CCK receptor.