Live cell imaging with protein domains capable of recognizing phosphatidylinositol 4,5-bisphosphate; a comparative study

Table 2 Ca²⁺ signaling parameters in ATP-stimulated COS-7 cells expressing either one of the mRFP-Tubby-domain, PLCδ1PH-mRFP and p130-PH-mRFP proteins

Construct	mRFP fluorescence (AU)	T_1/2activation* (sec)	N =
Tubby-domain	< 100	6.0 ± 0.3**	109
	101-1000	6.0 ± 1.8	31
	1001-5000	13.5 ± 3.5	40
	5001-10000	12.0 ± 1.5	4
PLCδ1PH	< 100	3.5 ± 0.4	99
	101-1000	6.5 ± 1.1	20
	1001-5000	12.5 ± 3.9	34
	5001-10000	18.0 ± 6.1	5
p130-PH	< 100	3.5 ± 0.4	91
	101-1000	12.0 ± 4.9	16
	1001-5000	19.5 ± 5.3	39
	5001-10000	> 100	17

* The lag time of the Ca²⁺ response was defined as the time it takes for a cell to reach half-maximum of its Ca²⁺ peak after addition of 50 μM ATP.
**Values are calculated from cells expressing the mRFP-tagged proteins at the indicated intensities. Note the largest effects of the p130-PH-mRFP protein that does not bind to the membranes but binds InsP₃ with comparable affinity to the PLCδ1PH-mRFP [27].

ISSN: 2661-8850