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. Author manuscript; available in PMC: 2016 Mar 3.
Published in final edited form as: Biochemistry. 2015 Feb 19;54(8):1681–1693. doi: 10.1021/bi501171r

Table 1.

Effect of Alanine Mutation on HXB2 Envelope Protein

Residue Cell-Cell Fusion Virus Entry
gp120a Level gp41b Level Fusione Category Effectf of alanine mutation gp120c Level gp41d Level Fusione Category Effectf of alanine mutation
L660A +++++ ++++ WT - ++++ ++++ WT -
L661A +++++ ++++ Diminished - ++++ +++ Diminished -
E662A +++++ ++++ WT - ++++ +++++ WT -
L663A ++++ +++ WT - ++++ ++++ Abolished Severe defect
D664A ++++ ++++ Abolished Severe defect ++++ ++++ Diminished -
K665A ++++ ++++ WT - ++++ ++++ Abolished Severe defect
W666A +++++ +++++ WT - ++++ +++ Diminished -
S668A +++++ ++++ Diminished - ++++ ++++ WT -
L669A +++ ++++ Diminished Mild defect +++ +++ Abolished Severe defect
W670A ++++ ++++ WT - ++++ ++++ Enhanced Increased Env Expression
N671A ++++ +++++ Diminished - ++++ ++++ Diminished -
W672A +++++ +++++ WT - ++++ ++++ WT -
F673A +++++ +++++ WT - ++++ ++++ Diminished -
N674A +++++ ++++ Diminished - ++++ ++++ Enhanced Enhanced fusogenicity
I675A ++++ ++++ WT - ++++ ++++ Diminished -
T676A +++++ +++++ WT - +++++ ++++ Diminished -
N677A ++++ +++++ Diminished - ++++ ++++ Diminished -
W678A +++++ +++++ WT - ++++ ++++ Diminished -
L679A +++++ +++++ WT - ++++ ++++ Abolished Severe defect
W680A +++++ +++++ Diminished - + +++ Abolished Association
Y681A ++++ +++++ Diminished - ++++ +++ Abolished Severe defect
I682A +++++ +++++ WT - ++++ ++++ Diminished -
K683A ++++ +++++ Diminished - ++++ +++ Abolished Severe defect
a, b

Protein (gp120 a, and gp41 b) levels were shown in the cell lysates used for cell–cell fusion and

c, d

Protein (gp120 c, and gp41 d) levels of expression shown in virus. The levels of protein expression were shown as follows: +, 0–20% of WT levels; ++, 20–50% of WT levels; +++, 50–80% of WT levels; ++++, >80% of WT levels; and +++++, >120% of WT levels.

e

Fusion categories were defined as follows: WT (no effect, WT level), diminished (20–80% of wild type), abolished (<20% of wild type), and enhanced ( >120% wild type).

f

Effect of alanine mutations were defined as follows, expression/folding (<20% of WT gp41), cleavage (<20% gp120 and gp41, WT level of gp160), association (<0.5of gp120/gp41 ratio), severe fusogenicity (>20 % of WT gp41, >0.5 gp120/gp41 ratio, < 20% of WT fusion level), mild fusogenicity (>20 % of WT gp41, >0.5 gp120/gp41 ratio, 20–80% of WT level), increased Env expression ( >120% of WT gp160 proteins and fusion level), and enhanced fusogenicity ( >120% of WT fusion, WT gp160 expression level.)