Unknown column in 'field list' error on MySQL Update query

I keep getting MySQL error #1054, when trying to perform this update query:

UPDATE MASTER_USER_PROFILE, TRAN_USER_BRANCH
SET MASTER_USER_PROFILE.fellow=`y`
WHERE MASTER_USER_PROFILE.USER_ID = TRAN_USER_BRANCH.USER_ID
AND TRAN_USER_BRANCH.BRANCH_ID = 17

It's probably some syntax error, but I've tried using an inner join instead and other alterations, but I keep getting the same message:

Unknown column 'y' in 'field list' 

Try using different quotes for "y" as the identifier quote character is the backtick (“`”). Otherwise MySQL "thinks" that you point to a column named "y".

See also MySQL 5 Documentation

Enclose any string to be passed to the MySQL server inside single quotes, e.g.:

$name = "my name"
$query = " INSERT INTO mytable VALUES ( 1 , '$name') "

Note that although the query is enclosed between double quotes, you must enclose any string in single quotes.

You might check your choice of quotes (use double-/ single quotes for values, strings, etc and backticks for column-names).

Since you only want to update the table master_user_profile I'd recommend a nested query:

UPDATE
   master_user_profile
SET
   master_user_profile.fellow = 'y'
WHERE
   master_user_profile.user_id IN (
      SELECT tran_user_branch.user_id
      FROM tran_user_branch WHERE tran_user_branch.branch_id = 17);