There is no rule that dictates which part of speech comes first in a sentence. Examples:
My brother is at college.
- the common noun 'brother' is the subject of the sentence.
- the noun 'brother' is preceded by the pronoun 'my' (a possessive adjective) as the first Word in the sentence.
Jeffrey who is at college is the oldest.
- The proper noun 'Jeffrey', the subject, is the first Word the sentence.
- The relative pronoun 'who' follows the noun 'Jeffrey' to introduce the relative clause.
The college he attends is in Texas.
- the common noun 'college' is the subject of the sentence preceded by the article 'the'.
- the personal pronoun 'he' (referring to brother Jeffrey) follows the common noun 'college' as the subject of the subordinate clause.
- The proper noun 'Texas' is at the end of the sentence.
