Why are there two bands when using the SS18-SSX Antibody #70929 and the SS18-SSX (E9X9V) XP® Rabbit mAb #72364?

Both the polyclonal SS18-SSX Antibody #70929 and the SS18-SSX (E9X9V) XP® Rabbit mAb #72364 were produced by immunizing animals with a synthetic peptide corresponding to residues surrounding the fusion site of human SS18-SSX protein. There are two SS18 isoforms that can be fused to SSX, hence the presence of two bands.

The SS18 (D6I4Z) Rabbit mAb #21792 also recognizes two distinct bands, corresponding to the two SS18 wild-type isoforms. The antigen used to produce the SS18 (D6I4Z) Rabbit mAb #21792 is downstream of the SS18 sequence (1-379) present in the fusion proteins and therefore #21792 does not detect the SS18-SSX fusions. 

Additionally, there are different SS18 fusions with SSX 1, 2, and 4; however, they are all the same size and based on sequence homology, both #70929 and #72364 should recognize all of them.

We currently have two antibodies that recognize SSX proteins, SSX (E5A2C) Rabbit mAb (Carboxy-terminal Antigen) #23855 and SSX1/3 (E9P5M) Rabbit mAb (Amino-terminal Antigen) #42734. The antigen sequence used to produce #23855 is present in the SSX sequence found in the SS18-SSX fusions (~111-178) therefore this antibody will recognize the fusion proteins as well as wild-type SSX 1-4.  The #42734 antibody was produced with an antigen sequence upstream of the SSX sequence present in the SS18-SSX fusion proteins, therefore this antibody will not detect the SS18-SSX fusions.

 

Last updated: February 27, 2024