No officer or employee of the department of banking shall be an officer, director, trustee, attorney, owner, shareholder, or partner in or of any financial institution. Nor shall any officer or employee of the department receive, directly or indirectly, any payment or gratuity from any financial institution, or be engaged in any manner in the negotiation of loans for others therewith. Nothing herein shall prohibit said persons from having shares as a result of membership in a credit union, mutual savings association, or similar depository institution by virtue of being a customer; nor shall it prohibit the receipt of interest or other payments on accounts made in the regular course of business.