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Biomedical subjects

J Drysdale

Publications and source records attributed to J Drysdale.

23 records · Page 2Linked to original sources

Human ferritin light chain gene sequences mapped to several sorted chromosomes.

The iron storage ferritin light-chain gene exhibits multiple restriction enzyme fragments which have been mapped by analyzing sorted human chromosomes. A dual laser chromosome sorter was used to construct spot-blot filter panels representing 22 chromosome fractions. Hybridization of radiolabeled human ferritin-L gene probe to spot-blot panels revealed the ferritin-L gene on more than one chromosome. Miniaturized restriction enzyme analysis was used to map each of the ferritin-L restriction fragments uniquely to one of three chromosomes. This combination of sorted chromosome analyses provides a rapid method to map homologous DNA sequences located on more than one chromosome.

Base Sequence↗

Isolation and characterization of a cDNA clone for human ferritin heavy chain.

Ferritin, the main iron-storage protein, is composed of two partially homologous subunits, heavy (H) and light (L), with MrS of 21,000 and 19,000, respectively. We have isolated a cDNA clone for human ferritin H chains by screening a human lymphocyte cDNA library with synthetic oligodeoxyribonucleotides. The oligonucleotide sequences were derived from two pentapeptides found in human spleen ferritin. The selected clone hybridized to both probes and selected H-chain mRNA, but not L-chain mRNA, when hybridized to HeLa cell mRNA. These results indicate that the cloned DNA codes for a H chain of human ferritin. Since the amino acid sequence derived from the cloned DNA was almost identical to the partial amino acid sequence of a minor component found in human spleen ferritin, we conclude that the minor sequence found in human spleen ferritin must be a H subunit. Genomic analysis gives a complex pattern that suggests that ferritin H chains are encoded by a multigene family or have an unusually large number of exons.

Base Sequence↗

Studies on heterogeneity in ferritin subunits.

Subunits prepared by dissociating rat and human ferritins by acid/urea or SDS can be resolved by isoelectric focusing in urea/Triton gels into many discrete forms. Most of these are not true isosubunits but aggregation artefacts formed during electrofocusing. The distribution of H and L subunit classes in these aggregates indicates that HeLa and heart ferritins contain similar classes of H and L subunits but that one or both of these classes is different in liver and kidney ferritins. To avoid aggregation artefacts, we examined subunits synthesised in vitro from exogenous mRNA. Our results indicate that HeLa and rat liver cells synthesise only one class of L subunit but two classes of H subunit.

Animals↗