TABLE 1.

Summary of HIV pairwise protein interactions^a

Protein 1-protein 2	Life stage(s)	Major function(s)	Positions in protein 1 (reference[s])	Positions in protein 2 (reference[s])	Reference(s)
GP120-GP41	Entry, budding	Promotes viral entry, promotes viral budding, promotes Env packaging	31–46, 50–54, 70–75, 84–89, 91, 103, 106, 107, 110, 111, 114, 215, 220–224, 226, 244, 246, 489–505 (50)	520–528, 530, 533, 534, 536, 537, 540, 541, 543–546, 569–572, 574, 575, 577–579, 581, 582, 585, 586, 588–592, 593, 596–598, 601–610, 614, 617–619, 622, 623, 628, 629, 631–633, 635, 636, 639, 642, 643, 646, 650, 651, 654, 658, 659, 661–663 (50)	48–58
GP41Env-matrix	Entry, budding	Promotes viral entry, promotes Env packaging	712, 713–856 (70, 84); 764–856 (591); 814–844 (73)	12, 30, 34 (76); 18, 20, 22, 32, 33 (83, 592); 6, 29, 31, 62 (74); 49 (84); 62 (72); 84, 99 (75)	69–76, 83, 84, 591, 592
GP120-Tat	Entry	Promotes viral entry	166–171 (89); 157–171 (86)	73–86 (86)	86, 89
RT-integrase	Reverse transcription, integration	Enhances RT activity, inhibits integrase activity	1–242, 387–421 (108)	201–288 (108); 243, 250, 258, 220–270 (102); 213–288 (106)	102, 106, 108
RT-nucleocapsid	Reverse transcription	Enhances RT activity	548–560, p51 domain (113)	13–30, 34–51 (110, 111)	110, 111, 113
RT-Vif	Reverse transcription	Enhances RT activity	?	161–164	131
RT-Tat	Reverse transcription	Enhances RT activity	?	49–57	139
RT-Nef	Reverse transcription	Enhances RT activity	p51 domain	154–172	148
Protease-Tat	Reverse transcription	Protease cleaves Tat to enhance reverse transcription	Protease catalytic site	49–57	152
Integrase-Rev	Integration	Inhibits integrase activity	66–80, 118–128 (173)	12–23, 53–67 (173)	173–175, 180
Integrase-matrix	Integration	Enhances nuclear import of the PIC	50–212	132	181
Matrix-Vpr	Integration	Enhances nuclear import of the PIC	88–132	?	183
Integrase-Nef	Integration	?	?	58–206	149
Tat-Vpr	Transcription	Enhances viral transcription	50–67	?	220
Tat-Rev	Transcription	Proteasomal degradation of Tat	?	35–50	216
Tat-Nef	Transcription	Enhanced viral transcription	?	?	223
Tat-nucleocapsid	Transcription	NC induces Tat degradation	?	?	228
Vif-Vpr	Transcription	Vif mediates Vpr degradation	?	?	232
NCGag-Vif	Budding	Vif packaging, viral core stability, inhibits PR cleavage	44–55 (301)	75–114 (300)	300, 301, 303
NCGag-Vpr	Budding	Vpr packaging	13–30, 34–51	70–80	313
p6Gag-Vpr	Budding	Vpr packaging	15–18 (329); 32–46 (325); 34–36 (326); 35–47 (330); 41–46 (322)	18–34 (322); 1–71 (327)	322, 325–327, 329, 330
p6Gag-Vpx	Budding	Vpx packaging	15–40 (333)	73–89 (333)	314, 332, 333
GP41Env-Nef	Budding	Env packaging	712–715	181–210	336
Gag-RT	Budding	RT packaging	183–305 (347)	?	347, 348
Protease-Gag/GagPol	Maturation	Gag and GagPol cleavage	Protease catalytic site	Gag/GagPol cleavage sites	495–497
Protease-Vif	Maturation	Inhibits protease activity	1–9 (516, 517)	30–65 (519); 41–65 (520); 78–98 (516); 81–88, 88–98 (521)	516, 517, 519–521
Protease-RT	Maturation	Protease cleaves RTGagPol, RT promotes protease activity, protease inhibits RT activity	Protease catalytic site	440 | 441	522, 593
Protease-Nef	Maturation	Protease cleaves Nef, Nef inhibits protease activity	Protease catalytic site	57 | 58	528
Protease-GP41CT	Maturation	Protease cleaves GP41CT	Protease catalytic site	714 | 715, 716 | 717	538

^aA question mark indicates that the corresponding information is not available. A vertical line indicates a protease cleavage site (e.g., 57 | 58 suggests that HIV protease cleaves the substrate protein between amino acid positions 57 and 58). Position indices of GP120 and GP41 are based on the Env protein sequence in the HIV-1 HXB2 reference strain. Except for HIV-2 Vpx, interaction domains are reported for HIV-1.