Human and sooty mangabey putative alternative coreceptors differ in extracellular regions. Seven-transmembrane receptors APJ, CCR2b, CCR3, CCR4, CCR8, CXCR4, CXCR6, GPR1, and GPR15 were cloned and sequenced from sooty mangabey, and predicted protein sequences were aligned to human sequences. Alignments between human and sooty mangabey extracellular domains, including the N-terminal domain (NTD) and extracellular loops (ECL), are shown.