HSP 70 family comprises four highly conserved proteins, HSP 70, HSC 70, GRP 75 and GRP 78, which serve a
variety of roles. They act as molecular chaperones, facilitating the assembly of multi-protein complexes;
participate in the translocation of polypeptides across cell membranes and to the nucleus; and aid in the proper folding of nascent polypeptide chains (1, 2). GRP 78 is localized in the endoplasmic reticulum (ER), where it receives imported secretory proteins and is involved in the folding and translocation of nascent peptide chains (2). Sorting of these proteins is dependent on a C-terminal tetrapeptide signal, usually KDEL in animal cells, and HDEL in S.cerevisiae (3).
The 2E7 clone recognizes the C-terminal peptide HDEL, a common version of the endoplasmic reticulum retention signal found in yeast, plant, nematode and other ER proteins. 2E7 specifically stains HDEL proteins in barnyard grass, beet, cotton, mung bean, sorghum and wheat (4).