Calponin binds G-actin and F-actin with similar affinity.
Calponins are actin-binding proteins that are implicated in the regulation of actomyosin. Calponin binds filamentous actin (F-actin) through two distinct sites ABS1 and ABS2, with an affinity in the low micromolar range. We report that smooth muscle calponin binds monomeric actin with a similar affinity (K(d) of 0.15 microM). We show that the arrangement of binding is similar to that of F-actin by a number of criteria, most notably that the distance between Cys273 on calponin and Cys374 of actin is 29A when measured by fluorescent resonance energy transfer, the same distance as previously reported for F-actin.
Ferjani
Imen
I
UMR 5539 (CNRS) Laboratoire de motilité cellulaire (Ecole Pratique des Hautes Etudes) Université de Montpellier 2, Place E. Bataillon, CC107, 34095 Montpellier Cedex 5, France.
Fattoum
Abdellatif
A
Maciver
Sutherland K
SK
Manai
Mohamed
M
Benyamin
Yves
Y
Roustan
Claude
C
D000199:Actins / Q000378:metabolism*; D000818:Animals; D001665:Binding Sites; D002135:Calcium-Binding Proteins / Q000378:metabolism*; D003545:Cysteine / Q000378:metabolism; D005456:Fluorescent Dyes / Q000378:metabolism; D008840:Microfilament Proteins / Q000378:metabolism*; D009124:Muscle Proteins / Q000378:metabolism*; D009130:Muscle, Smooth / Q000378:metabolism; D011485:Protein Binding; D011817:Rabbits; D013050:Spectrometry, Fluorescence; D000096985:Calponins
D000199:Actins; D002135:Calcium-Binding Proteins; D003545:Cysteine; D005456:Fluorescent Dyes; D008840:Microfilament Proteins; D009124:Muscle Proteins; D000096985:Calponins