Table 2. Summary of protein-protein interactions suggested by yeast two-hybrid analysis.

The experiment demonstrates that co-expression of CD63 and the carboxy-terminus of HKα₂ is required to support the growth of yeast in the absence of tryptophan, leucine, histidine, and adenine in the medium. The experiment also demonstrates that the extracellular domain of NKβ₁ interacts with the extracellular sequence of HKα₂ that extends between transmembrane transmembrane region 7 (M7) and 8 (M8), as predicted by the model of Colonna (13). r-extrNKβ₁-pGADT7 represents the extracellular domain of rat NKβ₁ that was cloned in the plasmid pGADT7. r-intNKβ₁-pGADT7 represents that the intracellular plus transmembrane sequence of rat NKβ₁ that was cloned in the plasmid pGADT7.

Lane	Plasmid	+W,+L,+H,+A	−W,+L,+H,+A	+W, −L, +H, +A	−W, −L, −H,− A
1	m-CT-HKα2-pGBKT7	+	+	–	–
2	m-CD63-pACT2	+	–	+	–
3	m-CT-HKα2-pGBKT7/m-CD63-pACT2	+	+	+	+
4	m-M7M8-pGBKT7/m-CD63-pACT2	+	+	+	–
5	m-M7M8-pGBKT7/r-extNKβ1-pGADT7	+	+	+	+
6	m-CD63-pACT2/r-extNKβ1-pGADT7	+	+	+	-
7	m-CD63-pACT2/r-intNKβ1-pGADT7	+	+	+	-