No laugh here,  but I bet this little amino acid has a lot to do with some of the function of the carbohydrate recognition domain.  Here is a Pymol view of guinea pig SP-A from residue 51 to 347, rotated to show this AA.  Someone out there knows exactly which on it is… i will try to find out.  In addition, I will post the ferret sequence from the same location (also residue 51 to end) to see if there is a similarity. RED arrow points to the spike.