He is the Ludwig Chair of Molecular Biology at Memorial Sloan–Kettering Cancer Center in New York City.

He was made professor there in 1971 and became chair of the Department of Biochemistry and Molecular Biology in 1980.

[1] Ptashne was the first scientist to demonstrate specific binding between protein and DNA, and his lifelong work has been the elucidation of the molecular mechanisms of switch between lytic and lysogenic lifecyle of bacteriophage lambda, as well as how the yeast transcriptional activator Gal4 works.

He was the originator of the "ball and stick" model of transcription factor function, demonstrating in bacteria and in yeast that they typically consist of separable regions that mediate DNA binding and interaction with transcriptional activators or repressors.

He won the Albert Lasker Award for Basic Medical Research in 1997,[1] and the Massry Prize from the Keck School of Medicine, University of Southern California in 1998.