1 Introduction Acid transport is required to support hydroxyapatite synthesis by, osteoblasts, and to mediate hydroxyapatite removal in bone repair or remodeling, by osteoclasts. We do an overview of major phosphate-producing and acid-producing transporters for bone production or resorption, with brief indication of context and supporting ion transporters. In subsequent sections, linkage of major cotransport support mechanisms, some in part hypothetical, are discussed in more detail.