Which amino acids would you expect to be particularly abundant at the entrance of a porin that is specific for phosphate ions?

Porin is a transmembrane proteinthat permits molecules or ions to flow through. The sort of material that may move through the central aqueous channel is determined by its size and the residues that develop at thetrans-membrane.

Porins are $\beta$-barrel structures with a central aqueous channel that is narrowed to produce $7\times 11A^{\circ }$elliptical pore. The channel can handle solutes with a diameter of more than 600D. The sort of material that may move through the central aqueous channel is determined by its size and the residues that develop at the trans-membrane. A solid core can be found in a $\beta$-barrel with eight strands. The diameter of the cross-section of porins grows enough to allow a pore for solute transport when the number of strands increases to 16 or 18 strands.

Hence,lysine and arginine are abundant near the onset of porin, which is phosphate ion specific.$7$