Neal C. Robinson, PhD

Professor Emeritus (Retired, UT Health San Antonio)


Ph.D. University of Washington
Post Doctoral: Duke Univ (Charles Tanford); Univ of Oregon (Roderick Capaldi)
Other Faculty Positions: Univ. of Oregon (Research Associate);
University of California, Davis (Instructor)


Research Emphasis: Structural Organization of Mitochondrial Electron Transport Complexes; Role of Cardiolipin in Mitochondrial Function
The goal of our research is to understand the biological role of the phospholipid cardiolipin (CL) within the mitochondrial inner membrane. Cardiolipin comprises ~20 percent of the phospholipids within the inner membrane, but is not a component of other eukaryotic membranes. Why this negatively charged PL is present in the inner membrane is poorly understood. Our research has shown that CL is not a passive component of the mitochondrial inner membrane, but is bound to integral membrane protein complexes. We presently are focusing on defining the CL requirement within three mitochondrial electron transport complexes: NADH dehydrogenase (Complex I), cytochrome bc1 (Complex III), and cytochrome c oxidase (Complex IV). Each of these multi-subunit protein complexes contains small numbers of tightly bound CL. It is now clear that CL bound to each of these complexes serves a structural role in that it stabilizes specific subunit interactions. In addition, our data have demonstrated that a single CL bound to cytochrome c oxidase is also functionally important. We are currently testing the hypothesis that this particular CL is bound at the entrance to one of the proton channels, where it facilitates proton entry into the binuclear center. Such a mechanism would explain the requirement of bound CL for maximal electron transport and proton translocation. It is now our purpose to determine: 1) the functional and/or structural role for CL within the two other complexes; 2) to map the location of the bound CL within each; and 3) to define a possible universal binding motif within the mitochondrial electron transport complexes.

These projects all take advantage of experimental approaches that were developed in our laboratory, i.e., 1) synthesis of arylazido-CL photo-labels; 2) analysis of subunit content using sensitive HPLC and mass spectrometry methods; 3) selective dissociation of subunits using mild structural perturbants; and 4) pressure-induced subunit dissociation. With these experimental approaches, we are now in a unique position to define the mechanism(s) by which tightly bound CL influences the function and/or structure of three key enzymes within the mitochondrial inner membrane. Successful completion of research projects will define the absolute requirement for cardiolipin within the mitochondrial inner membrane and help us understand its functional and patho-physiological importance.