The functional repressor parts of a tetrameric lac repressor-beta-galactosidase chimaera are organized as dimers.
The functional repressor parts of a tetrameric lac repressor-beta-galactosidase chimaera are organized as dimers. is a research paper published in Proceedings of the National Academy of Sciences (1976). On theSindex it has a DataRank of 5.3. It has been cited 67 times, with 64 citing works in its 1-hop citation network.
Abstract
The chimaeric protein repressor-galactosidase, in which fully active lac repressor is covalently linked to the active enzyme beta-galactosidase, was used as a system for probing the quaternary structure of lac repressor. Electron micrographs revealed repressor-galactosidase to be a tetrameric aggregate. When lac repressor, alone, was crosslinked with dimethyl suberimidate, dimers, trimers, tetramers, and oligomers of the protein subunit were produced, whereas crosslinking of the tetrameric repressor-galactosidase resulted in the production of only dimers of the chimaera. Treatment of lac repressor with iodine resulted in the formation of protein dimers; the same result was obtained with repressor-galactosidase. After limited proteolysis of lac repressor, no crosslinking was obtained after treatment with dimethyl suberimidate, whereas iodine still produced a covalent linkage. These results are interpreted as evidence that the lac repressor parts of the tetrameric repressor-galactosidase-chimaera are organized as dimers on the tetrameric-beta-galactosidase core. Because this chimaera has been previously shown to have normal repressor activity [B. Müller-Hill and J. Kania (1974) Nature, 249,561-563], we conclude that lac repressor still is biologically active as a dimeric aggregate.
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FAIR Checklist
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DataRank Breakdown
Base Score Contribution
0.633
From this paper's citation signal
Citation Network Contribution
4.6
From 58 citing papers with measurable signal
Top 1 citer driving the network score
Ranked by citation count — the same ordering the engine uses when summing log1p(Cq) over citers.
- The three operators of the lac operon cooperate in repression.The EMBO Journal1990492 citationsDataRank 17.5
Why this DataRank?
DataRank blends this paper's own citation count with the influence of the papers that cite it. Here, roughly 12% comes from its base citations and 88% from the citation network (58 citing papers contributed measurable signal).
- Base score B(p)
- log1p(citation_count) — grows sub-linearly, so a paper with 1,000 citations is not 10× a paper with 100.
- Network N(p)
- Σ over citers of log1p(Cq) ÷ max(outdegreeq, 1). Being cited by a highly-cited paper with few references counts most.
- Damping factor d = 0.85
- DataRank = (1−d)·B(p) + d·N(p) — the two cards above are each already multiplied by their share.
- Self-citations excluded
- Citers sharing any OpenAlex author ID with this paper are filtered out before the network sum.
Citers are pulled from OpenAlex sorted by cited_by_count:descand capped per paper, so when the cap binds we keep the highest-signal references and the score is reproducible across reruns.
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