Txhua chav tsev ribosomal muaj RNA nucleotide molecules thiab lawv cov proteins cuam tshuam. Thaum ob lub subunits no koom ua ke, nws tsim cov ribosomes nquag ntawm synthesis ntawm cov protein. Qhov kev koom ua ke ntawm ob lub subunits no tsuas yog ua los ntawm magnesium ions tam sim no hauv cell.
Yuav ua li cas ribosomal subunits tuav ua ke?
Ob lub subunits (30S thiab 50S) ntawm cov kab mob 70S ribosome yog tuav ua ke los ntawm 12 dynamic txuas nrog RNA–RNA, RNA–protein, thiab protein-protein kev sib cuam tshuam. Cov txheej txheem ntawm kev tsim choj, xws li seb tag nrho cov txuas hniav no tau tsim ib txhij los yog nyob rau hauv ib qho kev txiav txim, tsis to taub.
Yuav ua li cas ion yuav tsum tau rau kev koom tes ntawm ribosomal subunits?
Tshwj xeeb, magnesium ions ua lub luag haujlwm tseem ceeb hauv lub koom haum subunits, tRNA khi rau qhov chaw txiav txim siab, thiab feem ntau cov qauv thiab kev ruaj ntseg ntawm ribosome (16– 20). Raws li pom nyob rau hauv kab mob 70S ribosome, divalent hlau ions cuam tshuam los tuav lub ribosomal subunits ua ke (21).
Yuav ua li cas ion yuav tsum ua kom ob lub ribosomal subunits ua ke thaum lub sij hawm cov protein synthesis?
$Mg^{2+}$ yog qhov tseem ceeb rau ob txoj haujlwm tseem ceeb xws li kev ruaj khov ntawm cov qauv thib ob ntawm rRNA thiab khi ntawm cov protein ribosomal rau rRNA. Yog li, ion yuav tsum khaws ob chav ribosomal ua ke thaum lub sij hawm muaj protein ntausynthesis yog $Mg^+$. Cov lus teb raug yog kev xaiv B.
Ib yam twg yog lub luag haujlwm rau khi ob lub subunits ntawm ribosomes?
Mg2++ yog qhov nthuav dav di- thiab monovalent cations hauv cov hlwb hauv tag nrho peb lub npe, ua lub luag haujlwm tseem ceeb hauv cov qauv thiab kev ua haujlwm ntawm cov roj ntsha macromolecules. Ribosomes khi ib feem tseem ceeb ntawm tag nrho Mg2+ thiab K+ cations.
