- Protein to which a specific ligand or hapten is conjugated.
- Unlabeled protein introduced into an assay at relatively high
concentrations which distributes in a fractionation process in the same
manner as labeled protein analyte, present in very low concentrations.
- Protein added to prevent non-specific interaction of reagents with
surfaces, sample components, and each other.
- Protein found in cell membranes, which facilitates transport of a
ligand across the membrane.
PAC, 2004, 76, 1033
(Glossary of terms used in toxicokinetics (IUPAC Recommendations 2003))
on page 1043