Nature - 2019.08.29

Article reSeArcH

preconditioning are nearly lost in the hearts of Mitok-knockout mice
(as also shown by analysis of infarct size; Fig. 5e), which demonstrates

that mitoKATP is the molecular target of diazoxide—at least in this
pathological setting.

In conclusion, we have identified a protein complex that accounts for
ATP-sensitive K+ transport across the inner mitochondrial membrane,

composed of a channel-forming subunit (MITOK) and a regulatory
subunit that carries the ATP-binding domain (MITOSUR). Although

we do not exclude the possibility that other proteins could perform
similar activities in specific tissues^37 , the in vitro reconstitution of this

complex is sufficient to reliably recapitulate the main electrophysiologi-
cal properties and pharmacological profile of the long-sought mitoKATP

complex^13. The mitoKATP complex that we identify represents a poten-
tial mechanism for matching ATP availability to energy production,

and thus contributing to the homeostatic control of cellular metabolism
under stress conditions.

Online content
Any methods, additional references, Nature Research reporting summaries,
source data, extended data, supplementary information, acknowledgements, peer
review information; details of author contributions and competing interests; and
statements of data and code availability are available at https://doi.org/10.1038/
s41586-019-1498-3.

Received: 29 November 2017; Accepted: 25 July 2019;
Published online 21 August 2019.

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WT MITOK KO

GRP75

MITOK

75

kDa

35

50

0

10

20

30

40

50

Heart injury (% LDH release)

WT I/R +

vehicle

WT I/R +

diazoxide 30 μM

MITOK KO I/R +

vehicle

MITOK KO I/R +

diazoxide 30 μM

• 
  

• 
  

7

8

9

10

11

12

Non-treated

ATP

ATP + diazoxide 50 μM

1 min –0.5

0

0.5

1.0

1.5

2.0

Non-treated

86

Rb

+ inux

(cps mg

–1 protein (

×^10

–3))

86

Rb

+ inux rate

(normalized cps min

–1

)

ATP

ATP + diazoxide 50 μM

*

• 
  

WT MITOK KO

ab

c
d

e

WT MITOK KO

Diazoxide –+–+

35.3 ±

17.4

Infarct
size (%)

11.6 ±

12 .8 *

33.8 ±

17.1

27.2 ±

15.1

Fig. 5 | MITOK is required for diazoxide-induced cardioprotection.
a,^86 Rb+ flux in isolated mitochondria. n = 3 independent experiments.
b,^86 Rb+ uptake rate. n = 3 independent experiments, P ≤ 0.029 using
two-tailed Student’s t-test. c, Western blot of wild-type and MITOK-
knockout liver mitochondria. d, e, Heart injury after ischaemia–reperfusion
(I/R), evaluated as percentage of lactate dehydrogenase (LDH) release
(d, mean ± s.d., n ≥  5  independent mice, P < 0.001 using two-way
ANOVA with Holm–Sidak correction) or percentage of infarct area after
staining with 2,3,5-triphenyltetrazolium chloride (TTC) (e, mean ± s.d.,
n ≥ 7 independent mice, *P = 0.008). Single measurements are provided
in Source Data.

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