Cloning of genes encoding putative taste receptor proteins

利用逆转录聚合酶链反应和退化寡核苷酸引物，从牛味觉组织中扩增出g蛋白偶联受体（GCR）超家族两个不同亚家族的新成员。由多个cDNA克隆组成的A型受体克隆与推测的嗅觉受体亚家族具有显著的相似性，而单个B型克隆与推测的肽受体亚家族具有显著的相似性。A型克隆在肾和味觉组织中均有表达。大量研究表明，cGMP可能在味觉传导中起一定作用。例如，据报道，关酰环化酶定位于味觉细胞的微绒毛。利用退化寡核苷酸引物和逆转录聚合酶链反应，从大鼠和牛舌上皮细胞中扩增出编码鸟苷环化酶催化结构域的cDNA片段，以鉴定味觉组织中鸟苷环化酶的结构。三个新克隆，两个膜型环化酶（RAT GC-1, BOV GC-3）和一个可溶性型环化酶（RAT GC-2）。鼠GC-1除味觉组织外，分布于大鼠各组织。BOV GC-3与最近克隆的嗅觉特异性桂酰基环化酶相似，但又有所不同。大鼠GC-2被鉴定为可溶性冠酰环化酶α 2亚基的大鼠同源物。

Using reverse transcription-polymerase chain reaction and degenerate oligonucleotide primers, we amplified novel members of two different subfamily of G-protein coupled receptor (GCR) superfamily from bovine taste tissue. Type A receptor clones composed of multiple cDNA clones had significant similarity with putative olfactory receptor subfamily, while a single type B clone had significant similarity with peptide receptor subfamily. Type A clones were expressed in renal as well as in taste tissue.A number of studies have shown that cGMP may play some roles in taste transduction. For example, guanylyl cyclase is reported to be localized at microvilli of taste cells. To identify the structure of guanylyl cyclase in taste tissue, cDNA fragments encoding guanylyl cyclase catalytic domain wre amplified from rat and bovine tongue epithelium using degenerate oligonuclotide primers and reverse transcription-polymerase chain reaction. Three novel clones, two membrane type guanylyl cyclases (RAT GC-1, BOV GC-3) and one soluble type guanylyl cyclase (RAT GC-2). RAT GC-1 was distributed over various rat tissues in addition to taste tissue. BOV GC-3 was similar to but distinct from recent cloned olfactory specific guanlylyl cyclase. Rat GC-2 was identified as rat homologue of alpha2 subunit of the soluble guanylyl cyclase.