Protein compositions of the T4 prohead and mature head

Range Table - link
Organism Bacteriophage T4
Reference Leiman PG, Kanamaru S, Mesyanzhinov VV, Arisaka F, Rossmann MG. Structure and morphogenesis of bacteriophage T4. Cell Mol Life Sci. 2003 Nov60(11):2356-70. p.2358 table 1PubMed ID14625682
Primary Source See refs beneath table
Method Electron microscopy & SDS PAGE analysis
Comments P.2357 right column bottom paragraph: "The head of bacteriophage T4 is composed of more than 3000 polypeptide chains of at least 12 kinds of protein (table 1) and a 172-kbp dsDNA chromosome, which comprises 102% of the unique region of about 169 kbp. The molecular weight (MW) of the head and the genomic DNA are 194 MDa and 112 MDa, respectively [ref 17]." P.2359 right column bottom paragraph to p.2361 left column top paragraph: "Assembly of the T4 head (fig. 5) starts with the formation of the gp20 gp40 membrane-spanning initiation complex at the inner side of the cytoplasmic membrane [ref 26]. The function of gp40 is unclear, since it is not present in the assembled heads, but it renders gp20 competent to start the assembly process [ref 27]. Subsequently, gp21, gp22, gp67, gp68, IPI, IPII, IPIII, and gp alt (table 1) attach to the gp20-gp40 complex and form a scaffold, which is then coated by a shell of gp23 and gp24. The dimensions of this prohead are about 15–20% smaller than those of the mature head. The proteins gp68, IPI, IPII, IPIII, and gp alt are not required for assembly, but rather help to eliminate incorrectly assembled intermediates that form dead-end products of maturation."
Entered by Uri M
ID 112412