Identification in islets of Langerhans of a new rat alpha 2-adrenergic receptor.
The islets of Langerhans are richly innervated, and an inhibitory effect on insulin secretion, mediated through alpha 2-adrenergic receptors, appears to be an important physiological neural modulator of beta-cell function. An alpha 2-receptor was cloned from isolated newborn rat islets using a polymerase chain reaction (PCR) approach. This receptor was shown by sequencing to be a new rat alpha 2-receptor very similar to the human alpha 2-C2 receptor. No other alpha 2-receptor subtype was identified in normal islets by the PCR using alpha 2-receptor primers. This was also the only alpha 2-receptor subtype present in the exocrine pancreas and liver. In contrast, in the beta-cell line, beta TC3, the alpha 2-C2 receptor was not detected, but the alpha 2-C4 and alpha 2-C10 receptor subtypes were detected. It is suggested that the alpha 2-C2 subtype may be the principal alpha 2-receptor mediating inhibitory autonomic nervous system activity in the gastrointestinal tract. A comparison of the rat islet, pancreas, and liver alpha 2-receptor sequences reported here with previously reported alpha 2-receptor sequences indicates that the rat islet alpha 2-receptor is not the rat alpha 2-C2 homologue previously denoted as RNG alpha 2, but is a new, fourth rat subtype with an even higher similarity to the human alpha 2-C2 receptor.
Wang
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Gerontology Division, Beth Israel Hospital, Boston, MA 02215.
Pilkey
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D000375:Aging / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D003001:Cloning, Molecular; D017931:DNA Primers; D018076:DNA, Complementary / Q000096:biosynthesis; D005260:Female; D015723:Gene Library; D006801:Humans; D007515:Islets of Langerhans / Q000254:growth & development / Q000378:metabolism*; D008297:Male; D008969:Molecular Sequence Data; D010179:Pancreas / Q000254:growth & development / Q000378:metabolism*; D016133:Polymerase Chain Reaction; D051381:Rats; D017207:Rats, Sprague-Dawley; D018341:Receptors, Adrenergic, alpha-2 / Q000032:analysis / Q000096:biosynthesis*; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid; D013552:Swine
D017931:DNA Primers; D018076:DNA, Complementary; D018341:Receptors, Adrenergic, alpha-2