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T4 structure
T4 Head
T4 Head - table
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T4 Tail - table
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Table 1. The protein structure of the head of bacteriophage T4 (modified from Fokine et al. 2004, and Leimann et al. 2003)

 

Gene

Mass (kDa)

Size (number of amino-acid residues)

Number of copies in mature head

Location

21

18.5

♦

♦

internal core, proteinase

22

2.5

♦

♦

internal core, major protein

23

48.7

422

930

shell, major capsid protein

24

46.0

407

55

shell, vertices

67

3.9

♦

♦

internal core

68

15,7

♦

♦

internal core

Alt

75.9

682

40

internal core

Hoc

39.1

376

155

shell, outer surface

IPI

8.5

♦

♦

internal core

IPII

9.9

♦

♦

internal core

IPIII

20.4

♦

♦

internal core

Soc

9.7

80

810

shell, outer surface

italics - name of the gene

♦ - proteins forming a scaffold, coated with gp23 and gp24 during the maturation process. After prohead assembly, the scaffolding core structure is proteolytically removed and the core proteins are either totally or partially degraded. The degradation products of some core proteins remain inside the mature head. Only the internal proteins (IPI, IPII, and IPIII) are found in comparable amounts in the prohead and in their processed form (Kuhn et al. 1986).