Biomedical subjects

F van der Mark

Publications and source records attributed to F van der Mark.

12 recordsLinked to original sources

PubMed1992

The promoter of the rice gene GOS2 is active in various different monocot tissues and binds rice nuclear factor ASF-1.

A single copy gene has been isolated, termed GOS2, from rice. Sequence comparison revealed highly similar genes in mammals and yeast, indicating that GOS2 encodes an evolutionary conserved protein. GOS2 mRNA was detected in all tissues examined. When the upstream region was translationally fused to the reporter gene gusA it was found to drive expression in a variety of rice tissues and in cell suspensions of other monocot species following introduction by particle bombardment. Therefore, the GOS2 promoter is potentially useful for genetic engineering of monocots. A DNA-binding activity from rice, termed rice ASF-1, with similar binding specificity as the cloned tobacco transcription factor TGA-1a, was found to bind to a TGACG sequence motif in the GOS2 promoter. Possible roles for rice ASF-1 in the transcriptional activation of the GOS2 promoter are discussed.

Amino Acid Sequence↗

PubMed1983

Variable amounts of translatable ferritin mRNA in bean leaves with various iron contents.

RNA was isolated from bean leaves with various iron and ferritin contents. The amount of translatable ferritin mRNA in these RNAs was determined by wheat-germ cell-free translation and immunoprecipitation with anti-bean seed ferritin serum. The levels of ferritin mRNA present in total RNA of the leaves are reflected by the in vivo levels of ferritin in the corresponding leaf tissues. This implies that the iron-dependent regulation of phytoferritin synthesis, in contrast with the regulation of animal ferritin synthesis, occurs at the level of transcription.

Ferritins↗

PubMed1983

Phytoferritin is synthesized in vitro as a high-molecular-weight precursor. Studies on the synthesis and the uptake in vitro of the precursors of ferritin and ferredoxin by intact chloroplasts.

Evidence is presented that French-bean (Phaseolus vulgaris) seed ferritin is composed of one type of subunit with an apparent Mr of 26500. In normal and iron-loaded leaf tissues it is detected immunologically with an antiserum raised against purified bean seed ferritin and migrates in SDS (sodium dodecyl sulphate)/polyacrylamide-gel electrophoresis with the same mobility as the bean seed ferritin subunit. The biosynthetic pathway of ferritin in normal and iron-loaded leaves was investigated. RNA was extracted, fractionated into polyadenylated RNA and translated in a cell-free rabbit reticulocyte lysate and a wheat-germ-extract system. The products were identified by SDS/polyacrylamide-gel electrophoresis after indirect immunoprecipitation. In all cases the ferritin product had an Mr 5000 higher than that of the native subunit. Uptake and processing of the precursor form of ferritin from iron-loaded leaves by intact chloroplasts was demonstrated. This indicates that, in iron-loaded leaves, ferritin acts as a chloroplast protein. We propose that the ferritin precursor in normal leaves follows the same biosynthetic pathway. This suggests that the iron-buffering function of ferritin in plants takes place in the chloroplast and that non-functional cellular iron will accumulate in this cell organelle.

Carrier Proteins↗

PubMed1983