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#serine

2 public questions tagged with this topic.

Eukaryotes gene regulation

Enzyme charging tRNA Sec with serine is

Serine loading onto tRNASec uses ubiquitous seryl-tRNA synthetase SerRS, same dimeric class II enzyme charging canonical tRNASer isoacceptors. SerRS identity elements include long variable arm and discriminator base G73 recognized in tRNASec acceptor stem, compensating absence of typical G3:U70 marker. Reaction consumes ATP forming seryl-adenylate intermediate then transferring serine to A76 3' end. No separate SerRS isoform required for Sec pathway, reflecting economical reuse of translation machinery. Fidelity depends on downstream modifying enzymes PSTK and SepSecS rejecting unmodified tRNASec and tRNASer species. Hence canonical synthetase moonlights in selenoprotein pathway linking selenium utilization to central tRNA aminoacylation infrastructure across domains.

Ref: Alberts et al., Molecular Biology of the Cell, 7th ed., Chapter 6: SerRS Charging tRNASec

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Regulation of chromatin structure

Which histone modification commonly occurs on serine or threonine?

Histone tails contain hydroxyl-bearing residues capable of phospho-esterification. Serine and threonine side chains are phosphorylated by serine-threonine kinases such as Aurora B, MSK1, PKA and CK2, transferring γ-phosphate of ATP to hydroxyl oxygen. This introduces bulky negative charge, altering tail conformation and electrostatic interaction with DNA or reader proteins. Examples include H3S10, S28, T3 and H3T11 regulation during mitosis, DNA damage and transcriptional activation. Lysine and arginine cannot be phosphorylated in this context; they instead undergo acetylation and methylation, making phosphorylation specific to serine, threonine and tyrosine.

Ref: Lodish et al., Molecular Cell Biology, 9th ed., Chapter 8: Histone Phosphorylation Occurs on Serine and Threonine

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