Multiple MySQL connections + transactions

I ran into a bit of a snag in my code, and I'm trying to make heads or tails as to whether this will work.

From within my PHP script, can I write to a database using a MySQL connection in the middle of a transaction with a different connection?

e.g.

// Open Connection 1 and connect to Database A
// Start transaction with Connection 1
// Write some stuff with Connection 1
// Open Connection 2 and connect to Database B
// Write some stuff with Connection 2
// Close the transaction associated with Connection 1

This is probably the wrong terminology, but I hope you get the idea of what I'm trying to do here.