BIO 102 Unit 4 Part 2_ Cytoskeleton Notes

For actin fluorescently tag actin subunit linear line

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Unformatted text preview: oo thing) 4. for actin: fluorescently tag actin subunit Linear line! x-inter cept is critical concentration S lide 59: [polymer] at steady state: 1.8 T otal subunit concentration= equib-polymer (2-0.2) Nucleat ion is a 2- st ep react ion: --creates a dimer (unstable) --then another comes in, adds a tr imer (<--- nucleus) --can add more subunits on to both ends to form a filament C. Key Feat ures of act in/ MT A ssembly -during the elongation, phase rate of polymer elongation is linear - linearly dependent on total subunit concentration -rate of polymer along. is faster at the plus/barbed end than at the pointed (minus) end of the polymer -the cr it concentr ation for subunit addition is low er at the plus end than at the minus end (bias of subunit adding) -plus end is the fast disassembly end for both MTs and actin filaments aka plus end grows faster and at a lower crit concentration D. Key Feat ures of MT/ act in MT assembly : Lag in hy droly sis of bound nucleot ide aft er subunit addit ion t o poly mer -for both G-actin and tubulin dimer, nucleotide (NTP) hydrolysis occurs upon incorpor ation into polymer -how ever, hydrolysis occurs at a r ate slow er than subunit addition under conditions of high free subunits available for addition Actin filaments “age” from +‐>‐ end after subunit addition at the + end because AT P hydr olysis and then release of Pi are slow processes As a gr ow ing filament ages, subunits in the oldest par t of the filament will contain...
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This note was uploaded on 02/05/2014 for the course BIO 102 taught by Professor Chandhoke during the Fall '13 term at Yale.

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