N-LINKED GLYCOSYLATION INFLUENCES THE THE RMOSTABILITY OF RENIN

Inbred strains of mice, which produce high levels of submaxillary glan d (SMG) renin have two renin genes, Ren 1 and Ren 2, per haploid genom e, while strains with low levels of SMG renin have only the Ren 1 gene . Ren 1 codes for a glycosylated protein and Ren 2 codes for a highly homologous but unglycosylated and less thermostable protein. In order to determine if this difference in thermostability is related to the a bsence of glycosylation of renin-2 and/or to some aminoacid difference between both renins we have compared the thermostability of renin-2 a nd a renin-2 mutant containing two potential N-glycosylation sites add ed by in vitro mutagenesis. Both mutant and wild type renins were expr essed in AtT20 cells. Wild type renin was significantly less stable th an the glycosylated mutant form upon heating. Moreover, the kinetics o f heat inactivation of the mutant, in vitro deglycosylated form was si milar to that of the wild type renin. This result indicates that glyco sylation affects the thermostability of renin.