第五亞型蕈毒乙醯膽鹼受體刪除型及混合型受體之構築及表現

Abstract

G蛋白偶合受體其結構上均有穿進穿出細胞膜七次的特徵。有關於其結構和功能關聯性的研究，由於基因定位突變法和混合型突變種的運用，已漸趨明朗。為研究屬於G蛋白偶合受體一員的第五亞型蕈毒乙醯膽鹼受體其結構中和G蛋白作用的位置，以及其受磷酸化調控的機制，我們設計了三株刪除型突變種(刪除氨基酸序列269-290,268-364,269-290)及一株和人類β2腎上腺受體混成的混合型受體(氨基酸序列M5：1-251，β：262-413)。由哺乳動物細胞短暫質體表現法，發現此四株突變種均可表現於老鼠纖維母細胞株Lik的細胞膜上。有關功能上的改變，則需等到這四株突變種的穩定細胞株建立後才能進行。

Receptors coupled With G protein share a highly conserved structure transversing membrane seven times by alpha helical segments. The structure —function relationships of receptors are investigated based on the results of either site—directed mutagenesis or the construction of chimeric receptors. For study of the regions of M5 muscarinic acetylcholine receptor to react With the G protein and the possible desensitization mechanisms, We have constructed three deletion receptor mutants (delete the amino acid residues: 269—290,268—364269—448) plus one chimeric receptor between M5 and humen beta—2—adrenergic receptor (amino acid residues M5:1—251, beta—2: 264—413). By using transient expression in mouse Ltk cells, we have noticed that all four constructed mutants could express receptors on cell membrane. The further study on receptor — medicated cell function may wait the stable cell lines of the four mutants to be established.