Table 1.

Percentage of expression of Na⁺,K⁺-ATPase in MDCK cells contacts

Cell line	Animal species	Organ	Cell morphology	ATPase
MDCK	Dog	Kidney	Epithelial	100
CRFK	Cat	Kidney	Epithelial	45
CF2TH	Dog	Thymus	NA	37
PTK2	Marsupial rat	Kidney	Epithelial	10
LLCPK1	Pig	Kidney	Epithelial	6
Ma104	Monkey	Kidney	Epithelial	0
LLCMK2	Monkey	Kidney	Epithelial	0
NRK E52	Rat	Kidney	Epithelial	0
VERO	Monkey	Kidney	Epithelial	0
293	Human fetal	Kidney	Epithelial	0
CHO	Chinese hamster	Ovary	Epithelial	0
COS-7	Monkey	Kidney	Fibroblast	0
3T3	Mouse	Embryo	Fibroblast	0

Cells listed in the first column were labeled with CMTMR, mixed in 50:50 proportions with MDCK cells, plated at confluence and incubated overnight. Monolayers were then fixed, treated with a first antibody against the dog β₁-subunit, and a second, fluoresceinated one. These were then observed by confocal microscopy as described in Figure 1. One or two hundred borders between MDCK/other cell type were analyzed and scored positive if they exhibited green fluorescence staining. Last column on the right shows the proportion of heterotypic borders exhibiting β₁-subunit (except for the first line, where MDCK/MDCK have no heterotypic contacts). This subunit of Na⁺,K⁺-ATPase was present in 100% of the homotypic MDCK/MDCK contacts and in a lower proportion in heterotypic ones. NA, not available.