Graduate Teaching Assistants (TAs) are the subject of increasing attention in education research, both as partners in supporting the goals of research-based curricula, and as future faculty learning about the nature of physics instruction. In previous work, we began documenting TA beliefs and presented two contrasting case studies of TA beliefs about teaching physics. In this paper, we begin to build a framework that identifies categories of epistemological and pedagogical resources that TAs draw upon when talking about and when engaging in teaching practices. By applying this framework to observations and interviews of a set of TAs from an introductory physics course, we demonstrate emergent differences in how these instructors talk about their own teaching, as well as examples of how these differences appear to be reflected in their framing of the instructional activity. We conclude with implications for teacher preparation and professional development at the graduate level.