Microbiology Procedure

Index >> Bacteriophages - Part Two >> B OR Coat Proteins

B OR Coat Proteins

	B Or Coat Proteins - The capsid of the f2 phage consists of 180 subunits of the B or coat protein (MW 13,700) and one molecule of the A or maturation protein. The coat proteins are arranged in anicosahedral symmetry (T=3 surface lattice). The subunits of the particles are arranged as 20 hexamers forming the faces and 12 pentamers forming the vertices.
60 molecules of the coat protein form the 12 pentamers at the vertices of the icosahedron. The other 120 coat proteins form the hexamers corresponding to the 20 faces. The amino acid compositions of the coat proteins of f2, R17 and for have been determined. The compositions of M2 and MS2 are identical.
They differ from the amino acid sequence of f2 by the substitution of one methionine for leucine, and from that of R17 by the substitution of one glutamine glutamic acid (or leucine. The f2 coat protein (MW 13,750) consists of 129 residues without histidine.

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