猪鼻支原体膜蛋白p37酶切修饰的质谱分析

Mass Spectrometry Analysis Mycoplasma hyorhinis Lipoprotein p37 by Protease Cleavage

p37是猪鼻支原体的膜脂蛋白,有潜在的致癌活性.在对真核表达的p37蛋白分析时发现,p37表现为不同大小的分子片段,提示其存在蛋白质修饰.为了对p37的确切修饰进行分析,进而为其功能研究奠定基础,在构建不同融合蛋白表达质粒并证明其存在修饰蛋白的基础上,通过飞行质谱及N端氨基酸序列测定,分析了p37蛋白的精确分子量和酶切修饰的大致部位,发现3种形式的p37蛋白的精确分子量分别为47 644、46 105和43 984.p37蛋白在其N端被信号肽酶切去1个21肽,在其C端被蛋白酶切去1个18～26小肽后,成为分子量为43 984的成熟p37蛋白.对p37不同酶切修饰片段的分析将有助于对p37蛋白生物学功能及意义的研究.

p37 is a membrane lipoprotein of Mycoplasma hyorhinis. To understand its function in mammalian ceils, we analyzed the post-translation modification of membrane lipoprotein p37 and its biological functions in mammalian cells. With matrix-assisted laser desorption ionization-time of flight-mass spectrometry and N- terminal amino acid sequencing, we found when p37 was expressed in COS-7 ceils, there were three kinds of the proteins with different mass weights 47 644,46 105 and 43 984, respectively. The first 21 amino acids at the N-terminal and about 18-26 amino acids at the C-terminal were cleaved off by peptidase or protease. This procedure may be necessary for p37 to be mature and functional in mammalian cells.