sentence: Our finding that the SSH1-CPLV haploid is respiration deficient indicates that Ssh1p-CPLV lacks one or more functions of wildtype Ssh1p , and that this loss of function stresses the secretory pathway sufficiently to allow spontaneously occurring respiration deficient cells to have a growth advantage.Fusions to SEC61 have been shown previously to compromise Sec61p function to various degrees : an early C-terminal GFP fusion was viable only when overexpressed , a His6-tag at either N - or C-terminus reduces the speed of protein translocation through the channel into the ER , and a C-terminal 13 myc tag interferes with posttranslational import into the ER ( B. Wilkinson , pers .