Simple answer -
When your GPIO is LOW, output will be low. No problems. Your uC will sink the current.
When your GPIO is high, output will be high (upto 4.857v) , but ONLY if your load sinks MUCH less than 1.2mA.
However this depends on your uC's output port configuration. If it can source, then higher loads can be supported.
Since I see you are using Arduino, which implies AVR chips, then these can source around 20mA at least (within some limits). So it should be fine.
So the final question is - what is the load on this output ?