Nope. I pressume you would like to connect to your Notebook via USB. The USB cables are only to transmit signal, does not actually use USB protocol. (USB was chosen by manufacturers because the cables and headers are readily available and cheap)

I am sure it can be done with a custom adaptor with PCI-E -> USB interpreter or even a PCI-E to PCMCIA Int,

If by some chance you have a Notebook with a PCI-E x1 slot, Then you *could*, but if your notebook has a PCI-E x1 slot...chances are its a high end gaming Laptop anyway,(desktop in a flex box), would be interesting to see it done.

Either way, running a GFX card for gaming on the south bridge  (where the USB controller usually is), or from a PCI-E x1 slot is definitely not recommended. Bandwidth would be terrible. Game load times are bad enough these days.....