In this task, you are given a sentence. You are expected to recognize the name of gene or protein. Although there might be several correct answers, you need to write one of them.

Q:  To further identify the residues responsible for the activity , we isolated the mutant viruses that were not neutralized with the soluble form of MHV receptor proteins , since such mutants were expected to have mutations in amino acids responsible for receptor - binding activity .

A: MHV receptor proteins
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Q:  The longest cDNA insert identified was 2 . 2 kb and encoded the entire 462 - amino acid open reading frame of rat CgA including an 18 - amino acid hydrophobic signal peptide .

A: rat CgA
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Q:  This results in a decreased secretion of immunoglobulin A , and , consequently , a decreased resistance against infections .

A:
immunoglobulin A
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