A protein-based probe for detecting the presence of one of two distinct states of a target membrane-associated molecule by means of polarization microscopy is disclosed. The probe contains an anchoring moiety consisting of at least one lipidated peptide and/or at least one transmembrane α-helical peptide, a peptide linker moiety having the length of at least 5 amino acids, wherein at least 50% of the amino acids forming the linker are selected from glycine, serine, and threonine, a fluorescent moiety, and an affinity binding moiety capable of binding the target membrane-associated molecule. The moieties are arranged in the order a-b-c-d or d-c-b-a in the direction from the N-terminus to the C-terminus. Methods of detecting presence or absence of the target molecule, detecting activated or inactive forms of the target molecule, and detecting the activation of the target molecule are also described.

A mAb or Taxilin alpha-binding fragment thereof (“Taxilin alpha”) having an antibody heavy chain; an antibody light chain, an antibody comprising a heavy chain and/or an antibody. A kit of the same monoclonal antibody or Taxilin alpha-binding fragment thereof. A method of making the Taxilin alpha. The making method requires separating the Taxilin alpha from a cell culture that expresses the Taxilin alpha.

A method for diagnosis or aiding in the diagnosis of Sjgren's Syndrome (SS). The diagnosis method requires testing a sample obtained or derived from a subject for an amount of Taxilin alpha, wherein determining an amount of Taxilin alpha that is more than a reference comprises a diagnosis or aids in a diagnosis that the individual has SS, and wherein determining an amount of Taxilin alpha that is the same as or less than a reference indicates the individual does not have SS. A mAb or Taxilin alpha-binding fragment thereof (Taxilin alpha) having an antibody heavy chain; an antibody light chain, an antibody comprising a heavy chain and/or an antibody. A kit of the same monoclonal antibody or Taxilin alpha-binding fragment thereof. A method of making the Taxilin alpha. The making method requires separating the Taxilin alpha from a cell culture that expresses the Taxilin alpha.