What is the difference between transport proteins and effector proteins in gram-negative bacteria? When considering pathogenic gram-negative bacteria, is there any difference between the function of transport proteins and effector proteins? Or are they of the same functionality? Any reference would be very helpful.

> Is there any difference between the function of transport proteins and effector proteins?

Yes. In this context, the term "effector proteins" refers to proteins that are inserted into a host cell on infection to modulate host cell processes. Effector proteins are inserted into a host cell using a secretion system. The proteins involved in the secretion system are transport proteins, but the effector proteins themselves have a wide variety of functions. They include enzymes, transcription factors, and protein-protein interaction partners, and they have been shown to regulate many host cellular processes, from metabolism, to vesicular trafficking, cell adhesion, and apoptosis.

You can read more about this here. This review has an interesting perspective, and the Wikipedia page on Bacterial effector proteins isn't bad either.