en 23407609 R-Phycoerythrin (R-PE), a fluorescent protein from phycobiliprotein family, is isolated from red algae. Conjugation of antibodies to R-PE facilitates multiple fluorescent staining methods. In the present study polyclonal antibodies and polyclonal F(ab')2 fragment antibodies were conjugated to R-PE by two different methods. The efficiency of the methods was evaluated using Immunocytochemistry (ICC) and Sodium Dodecyl Sulfate Polyacrylamide Gel Electrophoresis (SDS-PAGE). In the first conjugation method, PE was attached to SMCC linker followed by conjugation of antibody to PE-SMCC. In the second method, SH groups were added onto R-PE molecule, while the antibody was attached to SPDP linker. Then, the antibody-SPDP molecule was conjugated to R-PE. Our results showed that the two conjugation methods did not have any abrogative effects on the antibody binding activity. Antibody, Conjugation, Immunocytochemistry, Phycoerythrin 87 92 https://www.ajmb.org/En/Article.aspx?id=34 https://www.ajmb.org/PDF/En/FullText/34.pdf JafarMahmoudianMonoclonal Antibody Research Center, Avicenna Research Institute, ACECR, Tehran, Iran114MahmoodJeddi-TehraniImmune and Gene Therapy Lab, Cancer Center Karolinska, Karolinska Institute, Stockholm, Sweden15HodjattallahRabbaniImmune and Gene Therapy Lab, Cancer Center Karolinska, Karolinska Institute, Stockholm , Sweden24Ahmad RezaMahmoudiMonoclonal Antibody Research Center, Avicenna Research Institute, ACECR, Tehran, Iran33Mohammad MehdiAkhondiReproductive Biotechnology Research Center, Avicenna Research Institute, ACECR, Tehran, Iran13Amir-HassanZarnaniNanobiotechnology Research Center, Avicenna Research Institute, ACECR, Tehran, Iran7LeilaBalaei GoliMonoclonal Antibody Research Center, Avicenna Research Institute, ACECR, Tehran, Iran119MahdokhtBabaeiMonoclonal Antibody Research Center, Avicenna Research Institute, ACECR, Tehran, Iran120RoyaGhodsMonoclonal Antibody Research Center, Avicenna Research Institute, ACECR, Tehran, Iran8