Psychrophrynella wettsteini Psychrophrynella wettsteini Psychrophrynella wettsteini is a species of frog in the family Craugastoridae. It is endemic to Bolivia and only known from the region of Unduavi in the Unduavi Valley, Sud Yungas Province, La Paz Department. Common name Wettstein's Andes frog has been coined for it. It is named for Otto von Wettstein, Austrian zoologist. "Psychrophrynella wettsteini" is a comparatively large species (maximum snout–vent length ) and has a robust body and long limbs. The snout is rounded. The tympanic membrane is absent, whereas the tympanic annulus is visible through the skin. Tips of the digits are only slightly swollen.
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