Table 2.

Summary of in vivo and in vitro phenotypes of N-terminal deletions of Est2p

Residues deletedSenescenceaTelomeresbPrimer extension activityc
None+++100
2–10+/−∼2
2–20+/−∼2
2–30++/−ND
2–50++/−ND
  • a Senescent strains (+) grew slowly on the initial transformation plate and gave rise to small colonies that are the same size as those from an Δest2 strain transformed with the pSE358 vector.

  • b Telomere lengths were determined in Southern hybridization assays (Fig. 2) and were scored as follows: +++, wild-type telomere length; +/−, on average about 300 bp shorter with weak hybridization signals.

  • c Primer extension assays were performed using TEL66 as primer under standard conditions. Each mutant fraction was assayed alongside the wild-type fraction (Fig. 3). The signals obtained from the mutant fractions were normalized against that from the wild-type fraction, which was taken as 100. ND, not determined.