Cofilin binds preferentially to ADPcontaining actin filament

Cofilin binds preferentially to ADP-containing actin filaments rather than to ATP-containing filaments. Consequently, this protein …

a. competes with profilin for actin binding.

b. binds to older actin filaments.

c. binds to the plus end of actin filaments.

d. stabilizes actin filaments.

e. All of the above.

Solution

ANS: b. binds to older actin filaments.

Cofilin binds preferentially to ADP-containing actin filaments rather than to ATP-containing filaments. Consequently, in the cell this protein can binds to older actin filaments and efficiently dismantles the older filaments to ensure all the actin filaments turn over rapidly.

Wrong Answers:

a. competes with profilin for actin binding

Profilin is antagonistic to the ADF/ Cofilin effect. So profilin never competes with cofilin.

c. binds to the plus end of actin filaments.

cofilin always binds to minus end, in plus end profilin will binds.

d. stabilizes actin filaments.

  Cofilin is a is a member of ADF (Actin depolymerizing factor) protein family. so it always promets dissociation of G-actin filaments. It never stabilizes actin filaments.