Rabbit Polyclonal Antibody to Ubiquitin Cat# RPCA-Ubi

      Ubiquitin is a globular 76 amino acid protein of about 8.5kDa molecular weight which was discovered by biochemical isolation from bovine thymus tissues (1). The protein was found to be highly conserved in amino acid sequence and was detectable in apparently every cell and tissue type, and, being apparently ubiquitously expressed, became known as ubiquitin. Subsequent work showed that ubiquitin has an important role in the targeting of proteins for proteolytic degradation, but has other important functions (2). Proteins to be degraded are covalently coupled to the C-terminus of ubiquitin as a result of the sequential activity of three families of enzymes, the ubiquitin-activating enzymes (E1s), ubiquitin-conjugating enzymes (E2s), and ubiquitin ligases (E3s). While humans express only two E1 enzymes, there are 35 E2 enzymes and hundreds of E3s. The ubiquitinated protein complex may then be degraded in the proteasome. Ubiquitin becomes covalently bonded to many types of pathological inclusions such as the neurofibrillary tangles of Alzheimer’s disease (3), the Lewy bodies of Parkinson’s disease (4), the Pick bodies of Pick’s disease (5) and many others. Ubiquitin can normally be removed from proteins to which it is bound and reused due to the activity of a large family of deubiquitinating enzymes.<

Chromogenic immunostaining of a NBF fixed paraffin embedded human hippocampus section from an Alzheimer’s Disease case. Rabbit pAb to ubiquitin, MCA-Ubi, dilution 1:2,000, detected with DAB (brown) using the Vector Labs ImmPRESS method and reagents with citra buffer retrieval. Hematoxylin (blue) was used as the counterstain. The RPCA-Ubi antibody strongly labels the cytoplasm of diseased neurons as identified by their morphology. Mouse select image for larger view.

1. Goldstein G, et al. Isolation of a polypeptide that has lymphocyte-differentiating properties and is probably represented universally in living cells.
PNAS 72:11-5 (1975).
2. Wilkinson K. The discovery of ubiquitin-dependent proteolysis. PNAS 102:15280-2 (2005).
3. Perry G. et al. Ubiquitin is detected in neurofibrillary tangles and senile plaque neurites of Alzheimer disease brains. PNAS 84:3033-6 (1987).
4. Kuzuhara S, et al. Lewy bodies are ubiquitinated. A light and electron microscopic immunocytochemical study. Acta Neuropathol. 75:345-53 (1988).
5. Murayama S. et al. Immunocytochemical and ultrastructural studies of Pick's disease. Ann. Neurol. 27:394-405 (1990).
6. Shaw G. Chau V. Ubiquitin and microtubule-associated protein tau immunoreactivity each define distinct structures with differing distributions and solubility properties in Alzheimer brain. PNAS 85:2854-8 (1988).