1IC2

DECIPHERING THE DESIGN OF THE TROPOMYOSIN MOLECULE

Summary for 1IC2

• Entry DOI: 10.2210/pdb1ic2/pdb
• Descriptor: TROPOMYOSIN ALPHA CHAIN, SKELETAL MUSCLE (2 entities in total)
• Functional Keywords: alpha-helical coiled coil, alanine, symmetry, axial stagger, bend, contractile protein
• Biological source: Gallus gallus (chicken)
• Total number of polymer chains: 4
• Total formula weight: 37094.17

Authors

Brown, J.H.,Kim, K.-H.,Jun, G.,Greenfield, N.J.,Dominguez, R.,Volkmann, N.,Hitchcock-DeGregori, S.E.,Cohen, C. (deposition date: 2001-03-29, release date: 2001-07-25, Last modification date: 2024-02-07)

Primary citation

Brown, J.H.,Kim, K.-H.,Jun, G.,Greenfield, N.J.,Dominguez, R.,Volkmann, N.,Hitchcock-DeGregori, S.E.,Cohen, C.
Deciphering the design of the tropomyosin molecule
Proc.Natl.Acad.Sci.USA, 98:8496-8501, 2001

PubMed Abstract: The crystal structure at 2.0-A resolution of an 81-residue N-terminal fragment of muscle alpha-tropomyosin reveals a parallel two-stranded alpha-helical coiled-coil structure with a remarkable core. The high alanine content of the molecule is clustered into short regions where the local 2-fold symmetry is broken by a small (approximately 1.2-A) axial staggering of the helices. The joining of these regions with neighboring segments, where the helices are in axial register, gives rise to specific bends in the molecular axis. We observe such bends to be widely distributed in two-stranded alpha-helical coiled-coil proteins. This asymmetric design in a dimer of identical (or highly similar) sequences allows the tropomyosin molecule to adopt multiple bent conformations. The seven alanine clusters in the core of the complete molecule (which spans seven monomers of the actin helix) promote the semiflexible winding of the tropomyosin filament necessary for its regulatory role in muscle contraction.

PubMed: 11438684
DOI: 10.1073/pnas.131219198

Experimental method

X-RAY DIFFRACTION (2 Å)