The RER have various proteins which have the role of assisting nascent proteins to fold rightly into their native conformation. Some of these are called as chaperones. RER-resident proteins are made on the RER and either pass into the lumen (as do secretory proteins) or are anchored in the membrane as for Type I integral membrane proteins. Furthermore, these proteins have a retention signal at the C terminus which is recognized by specific receptor proteins which retain these proteins in the RER, avoiding them from moving between the secretory pathway to the Golgi. In case of the soluble proteins in the lumen of the RER the retention signal is Lys-Asp-Glu-Leu or KDEL using the one-letter amino acid code at the C terminus. In case of the Type I integral membrane proteins in the RER membrane the retention signal is KKXX (Lys-Lys-Xaa-Xaa) in the cytosolic C terminus.