Phospho-specific Antibodies

MyBioSource Phospho-specific Antibodies Catalog Description

Phosphorylation is a key, reversible post-translational protein modification. It is the most common mechanism known for regulating protein function and many proteins have phosphoforms. The field of phosphoproteomics, a branch of proteomics, is dedicated to identifying, cataloging and characterizing proteins having one of more phosphate groups as a post-translational modification. However, researchers in every branch of science are interested in phosphorylation status and seek high quality, sensitive phosphospecific antibodies.

Several decades ago, the increasing recognition of the importance of protein phosphorylation led to a demand for research tools for specifically detecting the phosphorylated forms of proteins. This spurred the development of phosphospecific antibodies. The first phosphospecific antibodies were described in the 1980's, and the 1990's saw the development of more targeted approaches to develop sequence-specific phosphospecific polyclonal and monoclonal antibodies targeting specific phosphosites or putative phosphosites of a protein.

Phosphospecific antibodies continue to have key roles in showing that the tight regulation of phosphorylation statuses of proteins is essential for homeostasis and integral cellular processes such as cell growth and the cell cycle, as well as apoptosis and other cell death processes. They are helping us to understand that dysregulation of phosphorylation is associated with a myriad of diseases, among them cancer where constitutive phosphorylation can be associated with uncontrolled cellular proliferation.

Phosphospecific antibodies are commercially available for most of the common and even not so common targets researchers are studying.

MyBioSource has one of the largest collections of phosphospecific antibodies available worldwide.

From a technical standpoint, phosphoantibodies antibodies are typically designed to recognize specific phosphorms or phosphorylated residues of a protein. For example, for a given target there may be a phosphospecific antibody which recognizes phosphorylation of a protein at a particular serine residue whereas a separate phosphospecific antibody might recognize the target protein when it is phosphorylated at a tyrosine residue. For example, if you see an antibody listed as being to Ser35 of a given protein you can assume that is a phosphospecific antibody that recognizes the protein when it is phosphorylated at residue Ser35. Likewise, if the antibody is listed as being to Tyr35 the assumption is that the antibody recognizes the protein when it is phosphorylated at Tyr35.

Of course, the recognition site or epitope that a phosphospecific antibody binds to is based on the amino sequence used for immunogen. Many phosphospecific antibodies are made against phosphorylated synthetic peptides corresponding to an amino acid sequence which contains the target phosphosite. Antibodies made against the same sequence which hasn't been phosphorylated will recognize both phosphorylated and unphosphorylated forms of the protein.

It is important to recognize that unless an antibody is specifically stated as phosphospecific or specific to a particular phosphorylated residue, one can reasonably assume that the antibody will recognize both unphosphorylated and phosphorylated forms of a protein. This is because the epitopes recognized by general antibodies are typically phosphorylation independent. Today there are phosphospecific antibodies available for most any application that one can think of. This includes western blot analysis, immunohistochemistry of frozen or formalin-fixed, paraffin embedded tissue sections, immunofluorescence of cultured cells or cytospins, flow cytometry, and ELISA.

It is important to keep in mind that phosphorylation status is normally a dynamic process which is regulated by kinases and phosphatases.

Phosphorylation can be a fleeting process. Protein kinases phosphorylate proteins through the addition of a phosphate group which becomes covalently bound to the protein. The phosphorylated protein then functions through signal transduction pathways either activating or inhibiting downstream targets through signaling cascades. Phosphates then act to remove or cleave off the added phosphate group and return the protein to its basal state. This is important because constitutively phosphorylated proteins can cause or be the result of abnormal processes. Although most of the time, phosphophorylation is associated with protein activation, some proteins are inactivated by phosphorylation.

Because of the challenges associated with detecting fleeting protein states such as phosphorylation, many researchers use phosphospecific antibodies in parallel with antibodies that recognize all forms of the protein. This can be helpful for monitoring the overall expression of the protein with the general antibody along with identifying the phosphoforms with the phosphospecific antibody.