For standalone Premiere Pro Projects, there's Project Locking available. In Postlab, a Premiere Pro Project is added as a Document inside a Production. Once a Project's opened from a Production, Postlab locks it for exclusive use. If another Team Member accesses a Project, Postlab identifies who locked the Project, from which computer, and when.
Productions for Premiere Pro (i.e. a Premiere Pro Production, not a Postlab Production) is another approach. Currently, working with a Premiere Pro Production in Postlab can be achieved by storing the Premiere Pro Production directly on Postlab Drive. This automatically propagates Premiere Pro's lock files to all Team Members in real-time.