Tag Archives: FACT

4 Interesting papers

Here are brief summaries of 4 recent very interesting papers, each of which may be the subject of a future post (now that I’m not as worried about the effects of the Wuhan flu on family members over in Hong Kong).  They are likely behind a pay wall unfortunately

l. Watching an endoplasmic reticulum extruded tubule cut a P-body in half. Very significant as we begin to appreciate the phase transitions going on in our cells — for an overview of this see — https://luysii.wordpress.com/2018/12/16/bye-bye-stoichiometry/.

The paper(s) itself [ Science vol. 367 pp. 507 – 508, 537, eaay7108 ’20 ]

2. Watching microglia caress the cell body (soma) of neurons [ Science vol. 367 pp. 510 – 511, 528 – 537 ’20 ].  They’re actually rather creepy, extending processes and feeling up neurons, removing synapses from processes.  They use receptors for ATP and ADP to detect when a neuron is in trouble.  A new cellular specialization is described — Somatic Purinergic Junctions — a combination of mitochondria, reticular membrane structures, vesicle-like membrane structures and clusters of a particular voltage gated potassium channel (Kv2.1)

3. The ubiquitin wars inside a macrophage invaded by TB [ Nature vol. 577 pp. 682 – 688 ’20 ]  Ubiquitin initially was thought to be a tag marking a protein for destruction.  It’s much more complicated than that.  A host E3 ubiquitin ligase (ANAPC2, a core subunit of the anaphase promoting complex/cyclosome) promotes the attachment of lysine #11 linked ubiquitin chains to lysine #76 of the TB protein Rv0222.  In some way this helps Rv022 to suppress the expression of proinflammatory cytokines.

4. FACT (FAcilitates Chromatin Transcription)  is a heterodimer of two proteins which form a heterodimer [ Nature vol. 577 pp. 426 – 431 ’20 ].  If you’ve ever wondered how the monstrously large holoenzyme of RNA polymerase II, manages to work its way around the nucleosome copying one strand, you need to know about FACT, which basically grabs the disclike nucleosome with DNA wrapped around it twice, grabs both H2A-H2B dimers and holds them outside while pol II passes.  You have to wonder which came first the nucleosome or FACT. Neither would be of much use by themselves.  Probably they both grew up together, but it’s hard to envision the intermediate stages.