More Cell Codes and Authentication Mechanisms
Here are more “cool cell tricks” that ensure a smoothly-functioning system inside the cell that can adapt to changes while protecting assets.
- Ribosome code: Why don’t all ribosomes look alike? Perhaps they know a secret code. Another possible coding mechanism has been found in ribosomes, those important organelles in the cytoplasm that translate messenger RNA into proteins. You might recall that in chromosomes, a “histone code” appears to oversee the genetic code, regulating what genes get translated (07/26/2006, 07/28/2004). Now, researchers at Harvard Medical School reported in Cell1 that a similar mechanism might be at work in the ribosomes:
Our data supports a model in which there are many different forms of functionally distinct ribosomes in yeast, where the functional specificity is determined by the combination of duplicated ribosomal proteins present. However, protein composition is not the only source of ribosomal heterogeneity. Many fungi express different forms of 5S rRNA… Moreover, ribosomal proteins are subject to a variety of posttranslational modifications….; such modifications impact the translational activity of the protein…. Indeed, as previously posited…, there is a wealth of evidence for heterogeneity among ribosomes regulating the translational activity of their targets.
This model of translational regulation bears a striking resemblance to the canonical model for transcriptional regulation…. In sum, the transcription state of a given region of chromatin is determined by specific combinations of histone proteins, posttranslational modifications of histones, and DNA modifications; this complex relationship has been called the “histone code” (Jenuwein and Allis, 2001). Our data support a similar level of complexity for the process of translation in which different combinations of ribosomal protein paralogs, posttranslational modifications of ribosomal proteins, different forms of rRNA, and modifications to the rRNA allow calibrated translation of specific mRNAs. As with the histone code, this “ribosome code” would provide a new level of complexity in the regulation of gene expression.
- Token authentication: Here’s a design challenge for the engineer in you. A round door needs to be open to the environment, but keep interlopers out. Valid users, coming in a wide variety of sizes, need to be allowed access by an automatic authentication system that will usher them in quickly. Once inside, they should not be able to drift back out. The nuclear pore complex appears to use a most elegant solution to this problem of “selective gating.” It was reported in Science October 26 by researchers in Switzerland and Singapore.2
To spare our readers the technical nomenclature, we’ll substitute a sci-fi analogy for what happens at the 40-nanometer scale. Imagine a spaceship with a highly-sensitive computer center at its core. Objects and spacemen drift by in this weightless environment. The doors to the computer center must remain open at all times, but entry must be protected from enemies and from those who have no business being in there. Anchored to the rims of these doors are chains that extend outward, drifting about like spaghetti in a breeze tied at one end. The ends of these chains contain crystals that emit a force-field, collectively creating an invisible dome of force around the door, preventing accidental or malicious entry.
You, as a valid user, approach the door with a secret crystal in your hand that acts like an authentication token. When you extend it toward the chains, they sense it, and rapidly collapse backwards, pulling you in and forming a kind of tunnel around you. The more distant chains are not affected; they continue to stand guard and keep the force field up. Once you are inside, a robotic device removes your token and secures it in a protective chamber so that it cannot open the door behind you. Meanwhile, the collapsed chains quickly extend outward again, re-establishing the force field to keep out anything or anybody not having the special token.
Want the details? Read footnote 3 for the technical description of the nuclear pore complex authentication mechanism as described by the researchers.3
1. Komili, Farny, Roth and Silver, “Functional Specificity among Ribosomal Proteins Regulates Gene Expression,” Cell, Volume 131, Issue 3, 2 November 2007, pages 557-571.
2. Lim, Fahrenkrog, Koser, Schwarz-Herion, Deng, and Aebi, “Nanomechanical Basis of Selective Gating by the Nuclear Pore Complex,” Science, 26 October 2007: Vol. 318. no. 5850, pp. 640-643; DOI: 10.1126/science.1145980.
3. Ibid, “The nuclear pore complex regulates cargo transport between the cytoplasm and the nucleus. We set out to correlate the governing biochemical interactions to the nanoscopic responses of the phenylalanineglycine (FG)�rich nucleoporin domains, which are involved in attenuating or promoting cargo translocation. We found that binding interactions with the transport receptor karyopherin-[Beta]1 caused the FG domains of the human nucleoporin Nup153 to collapse into compact molecular conformations. This effect was reversed by the action of Ran guanosine triphosphate, which returned the FG domains into a polymer brush-like, entropic barrier conformation. Similar effects were observed in Xenopus oocyte nuclei in situ. Thus, the reversible collapse of the FG domains may play an important role in regulating nucleocytoplasmic transport.”
Cells are so high-tech cool, who could ever imagine they sprung out of a chaotic soup of dilute chemicals? Darwinists, that’s who – and they are on a campaign to teach their nonsensical scenario without competition by outlawing anyone who disagrees with them. Intelligent design – that is real, realistic science. The power is in the details.