Table 1 Frequency of non-consensus amino acids in each of the β20–β21 residues among 2500 primary HIV-1 strains (All) and among those HIV-1 strains that contain a residue other than leucine at position 193 (L193x)

From: The β20–β21 of gp120 is a regulatory switch for HIV-1 Env conformational transitions

Residue

All (%)

L193x (%)

Enrichmenta

Residue

All (%)

L193x (%)

Enrichment

I420x

1

2

2

E429x

55

39

0.7

K421x

8

6

0.75

V430x

10

12

1.2

Q422x

1

2

2

G431x

1

2

2

I423xb

9.5

29

3.1

K432x

61

43

0.7

I424x

25

33

1.3

A433x

2

2

1

N425x

9

14

1.6

M434x

12

6

0.5

M426x

16

27

1.7

Y435x

1

0

0

W427x

1

0

0

    

Q428x

2

2

1

Average

  

1.2

  1. aEnrichment, ratio of the frequency among non-leucine 193 HIV-1 strains to the frequency among all HIV-1 strains. The values associated with the maximal enrichment are indicated in bold.
  2. bP value < 0.00001 in a two-tailed t test for the difference between the enrichment of I423x and other residues
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