Member of the two-component regulatory system AlgB/KinB involved in regulation of alginate biosynthesis genes. Positive regulator of the alginate biosynthetic gene AlgD. Glycan biosynthesis; alginate biosynthesis [regulation]. Phosphorylated by KinB. In vivo phosphorylation of AlgB is not required for its role in alginate production. The mechanism by which it activates AlgD appears not to be mediated by conventional phosphorylation-dependent signal transduction.