used for the plots; lacking such, they suggest a very
strong bias in data acquisition or selection, thus throwing
into question all other results presented.
A somewhat different — albeit equally worrisome
point — is that the large capacitive currents in Fig. 8D
and E, again uncommented by the authors, indicate
severe technical problems with either data acquisi-
tion or processing and open to doubt all point plots
which are not directly supported by displayed current
Thus, this paper is deeply flawed in its failure to
acknowledge my substantial contribution to the actual
work, in its significant unadmitted reuse of previously
published descriptions of methods, and — in my judg-
ment — in its improper handling of the data actually
obtained. That is a pity, because a precise and clear
demonstration in Saccharomyces of the properties of a
novel membrane transporter from Schizosaccharomyces
would have been important. As this paper stands, how-
ever, its very structure puts all of its conclusions in
Dr. Adam Bertl
Botanisches Institut I
Universita¨t Karlsruhe (TH)
Bertl, A., Slayman, C.L., Gradmann, D. 1993. Gating and conductance
in an outward-rectifying K
channel from the plasma membrane of
Saccharomyces cerevisiae. J. Membrane Biol. 132:183–199
Bertl, A., Anderson, J.A., Slayman, C.L., Gaber, R.F. 1995. Use of
Saccharomyces cervisiae for patch-clamp analysis of heterologous
membrane proteins: Characterization of Kat1, an inward-rectifying
channel from Arabidopsis thaliana, and comparison with en-
dogenous yeast channels and carriers. Proc. Natl. Acad. Sci. USA
Lichtenberg-Frate´, H., Reid, J.D., Heyer, M., Ho¨fer, M. 1996.
The SpTRK gene encodes a potassium-specific transport protein
TKHp in Schizosaccharomyces pombe. J. Membrane Biol.
Reply to: The SpTRK Gene Encodes a
Potassium-specific Transport Protein
in Schizosaccharomyces pombe
Received: 13 May 1997
Our failure to acknowledge Dr. Adam Bertl was defi-
nitely an oversight that we deeply regret. However, Dr.
Bertl is not right when he comments that ‘‘. . . patch-
clamp experiments were learned by explicit instructions
in my laboratory’’ since we have already published two
papers (Ramirez, Vacata, McCusker, Haber, Mortimer,
Owen and Lecar: Proc. Natl. Acad. Sci. USA 86:1989,
7866–7870, and Vacata, Ho¨fer, Larsson and Lecar: J.
Bioenerg. Biomembr. 24, 1993, 43–53) using patch-
clamp techniques on yeast protoplasts.
The points of criticism by Dr. Bertl are mostly emo-
tional and polemical. To avoid endless argumentation
we prefer not to answer each point in detail. Instead, we
would like to emphasize some facts that may help to
clear the issue:
● Concerning M. Heyer’s visit to Dr. Bertl’s laboratory,
he stayed there for only two days, consulting on patch-
clamp experiments in the whole-cell mode on Saccha-
romyces cerevisiae wild-type protoplasts with another
● The patch-clamp measurements in the article represent
only a part of a comprehensive work on isolation and
molecular characterization of the K-transport on
Schizosaccharomyces pombe. Nevertheless, we
apologize for the missing reference to Bertl et al., J.
Membrane Biol. 132:183–199 (1993) in the Materials
and Methods section which regrettably disappeared
during our processing of the manuscript.
● The comparison of methods given by Dr. Adam
Bertl are due to the fact that these methods had al-
ready been published and we had cited both relevant
● The results were reviewed by independent reviewers
of The Journal of Membrane Biology upon whose se-
lection we had no influence.
● Specific points of criticism:
1. The discrepancy between Fig. 8B and E. This is
indeed a faulty attempt to standardize the three
diagrams 8A, B and C. However, the main evi-
dence remains, viz., there was no inward current
in the mutant at negative voltages, irrespective of
the way of plotting.
2. The apparent discrepancy in the transporter
conductance in Figs 8 and 10, vs. Fig. 9. The
measurements of the transporter conductance
with different cations were carried out with-
in several days using consecutively grown
cell batches. The four sets of data points in Fig.
9A–D were obtained with always one patch
by changing the ionic composition of the bath
solution. The 6 patches which provided the
data for Fig. 9 indeed differed in the basic
3. Leak current correction. The quality of a particu-
96 Letters to the Editor