Atelopus petersi Atelopus petersi Atelopus petersi is a species of toads in the family Bufonidae. It is endemic to Ecuador and is known from the Cordillera Oriental in the Napo Province and more provisionally, in the Chimborazo Province. The specific name "petersi" honors James A. Peters, an American zoologist who collected the first specimens of this species in 1962 and provided a description under the name "Atelopus pachydermus". Common names Peters' stubfoot toad and Peters' jambato toad have been coined for it. Adult males measure and adult females in snout–vent length. The snout is acuminate. The tympanic membrane, annulus, and stapes are
Integral membrane protein at atomic resolution by X-ray crystallography or nuclear magnetic resonance spectroscopy. They are challenging subjects for study owing to the difficulties associated with extraction and crystallization. In addition, structures of many water-soluble protein domains of IMPs are available in the Protein Data Bank. Their membrane-anchoring α-helices have been removed to facilitate the extraction and crystallization. Search integral membrane proteins in the PDB (based on gene ontology classification) IMPs can be divided into two groups: The most common type of IMP is the transmembrane protein (TM), which spans the entire biological membrane. Single-pass membrane proteins cross the membrane only once, while