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Biomedical subjects

G R Fink

Publications and source records attributed to G R Fink.

268 records · Page 15Linked to original sources
PubMed1972

Curing of a killer factor in Saccharomyces cerevisiae.

Many standard laboratory stocks of yeast are able to kill other yeast strains. This property has not been generally recognized because killing is observed only at low pH and not at the pH of standard media. In all strains examined, the genetic determinant for the killer trait shows non-Mendelian inheritance. The segregation patterns of our killer strains indicate that this killer determinant may be different from the killer previously described. Treatment of a killer strain with cycloheximide, but not with ethidium bromide, converts it into a sensitive nonkiller.

Antibiosis↗
PubMed1969

Nonsense mutations affecting the his4 enzyme complex of yeast.

The his4 region of yeast contains the information necessary for the catalysis of three steps in the histidine biosynthetic pathway. The three activities specified by this region remain physically associated during gel filtration and ultracentrifugation and after extensive purification. Nonsense mutations in the "operator distal" his4C region lower the molecular weight of the two proximal activities. The proximal activities can, therefore, function without the his4C portion of the protein(s). These observations are compatible with the following three possibilities. The his4 region codes for: (1) an aggregate of three proteins forming a multiprotein complex; (2) a single protein with three catalytic activities; and (3) a single protein which is cleaved to form three proteins which remain associated.

Chromatography, Gel↗
PubMedDate not supplied

Post-transcriptional control of the Arabidopsis auxin efflux carrier EIR1 requires AXR1.

The auxin efflux carrier EIR1 (also known as AGR and AtPIN2) is a key mediator of the response of Arabidopsis roots to gravity [1,2]. This response is thought to require the establishment of a transient auxin gradient in the root meristem, resulting in differential cell elongation [3]. Recent reports suggest that EIR1 is essential for the asymmetric distribution of auxin in the root meristem [4-7], but the regulatory aspects of this process are still not fully understood. Here, we studied the regulation of EIR1 in Arabidopsis using two reporters: one was a translational fusion that contained the entire EIR1 coding sequence, and the other a transcriptional fusion that had no EIR1 coding sequence. We found that EIR1 is controlled at the post-transcriptional level. The translational fusion was unstable in response to changes in auxin homeostasis, and was destabilized by cycloheximide. In contrast, the protein was stabilized in the axr1-3 mutant, which is auxin resistant and defective in auxin responses such as root gravitropism [8,9]. AXR1 is thought to participate in ubiquitin-mediated control of protein stability [10-12]. The dependence of EIR1 reporter expression on auxin concentrations and AXR1 suggests that auxin transport is regulated through a feedback regulatory loop that affects protein stability in response to auxin.

Arabidopsis↗
PubMedDate not supplied

Yeast plasma membrane ATPase is essential for growth and has homology with (Na+ + K+), K+- and Ca2+-ATPases.

The plasma membrane ATPase of plants and fungi is a hydrogen ion pump. The proton gradient generated by the enzyme drives the active transport of nutrients by H+-symport. In addition, the external acidification in plants and the internal alkalinization in fungi, both resulting from activation of the H+ pump, have been proposed to mediate growth responses. This ATPase has a relative molecular mass (Mr) similar to those of the Na+-, K+- and Ca2+-ATPases of animal cells and, like these proteins, forms an aspartylphosphate intermediate. We have cloned, mapped and sequenced the gene encoding the yeast plasma membrane ATPase (PMA1) and report here that it maps to chromosome VII adjacent to LEU1. The strong homology between the amino-acid sequence encoded by PMA1 and those of (Na+ + K+), Na+-, K+- and Ca2+- ATPases is consistent with the notion that the family of cation pumps which form a phosphorylated intermediate evolved from a common ancestral ATPase. The function of the PMA1 gene is essential because a null mutation is lethal in haploid cells.

Adenosine Triphosphatases↗