Immunoprecipitation Assay to Study Enzyme Receptor Interactions in Transfected Cells

Abstract

Source: Strazza, M., et al. Co-immunoprecipitation Assay for Studying Functional Interactions Between Receptors and Enzymes. J. Vis. Exp. (2018).

In this video, we demonstrate a technique to perform the co-immunoprecipitation of GFP-tagged wild-type and mutated PD-1 proteins using beads coated with anti-GFP antibodies. The bead-bound PD-1-GFP proteins are incubated with SHP2 proteins that interact with PD-1, enabling the identification of specific structural motifs in PD-1 that play a critical role in SHP2 interaction.

Protocol

1. Immunoprecipitation NOTE: The following steps should be performed on ice or at 4 °C. Supplement the lysis buffer (50 mM Tris-HCl at pH 7.2, 250 mM NaCl, 0.1% NP-40, 2 mM EDTA, 10% glycerol) with protease inhibitors (dissolve 1 tablet in 10 mL of lysis buffer) and with 1 mM sodium orthovanadate. Add 500 µL of ice-cold lysis buffer to the cells and remove and collect the cells from the plates immediately using a cell scraper. NOTE: </stron…

Representative Results

Figure 1: Experimental conditions and strategy. GFP-PD-1 WT (wild type), GFP-PD-1 Y223F (ITIM mutant), or GFP-PD-1 Y248F (ITSM mutant) were expressed in HEK 293T cells that were subsequently treated with pervanadate. Phosphorylated GFP-PD-1 proteins collected by GFP immunoprecipitation were mixed with lysates from cells overexpressing SHP2, and the levels and activity of SHP2 bound to each vers…

Materials

Nitrocellulose membranes	General Electric	10600004
Microcentrifuge	Eppendorf	5424-R	1.5 mL
BCA	Fisher	23225	Bi Cinchoninic Acid assay
Anti-SHP2	Santa Cruz	SC-280
Anti–GFP-agarose	MBL	D153-8
Anti-GFP	Roche	118144600
Anti-Actin	Santa Cruz	SC-1616
HEK-293 cells	ATCC	CRL-1573
Orthovanadate	Sigma	S6508
Protease inhibitor cocktail	Roche	11836170001	EDTA-free
Tris-Glycine SDS Sample Buffer (2x)	Invitrogen	LC2676	Modified Laemmli buffer
4-20% Tris-Glycine Mini Gels	Invitrogen	XP04205BOX	15-well
Trypsin-EDTA (0.25%) Phenol Red	Gibco	25200114
NaCl	Sigma	S7653	Sodium chloride