Which property is necessary for protein a to bind to protein b?

Protein A must have regions of shape and charge that are complementary to those on Protein B.

Explanation:

-Molecular shape determines how biological molecules recognize and respond to one another with specificity. Biological molecules often bind temporarily to each other by forming weak interactions, but only if their shapes are complementary, and if their functional groups and surface charges are compatible. The role of molecular shape illustrates how biological organization leads to a match between structure and function, one of biology's unifying themes.

the sugar-phosphate backbone forms the structural framework of nucleic acids, including dna and rna. this backbone is composed of alternating sugar and phosphate groups, and defines directionality of the molecule.